Add support for build_opt.h in the sketch folder to use additional global build options (#5237)

Additional compile arguments can be given by a file named "build_opt.h".
This enables users to easily extend their arguments on a central place.
The script has been taken from stm32duino's Arduino_Core_STM32 package
Co-authored-by: Me No Dev <me-no-dev@users.noreply.github.com>

platform.txt

@@ -111,6 +111,10 @@ build.loop_core=
 build.event_core=
 build.extra_flags=-DESP32 -DCORE_DEBUG_LEVEL={build.code_debug} {build.loop_core} {build.event_core} {build.defines} {build.extra_flags.{build.mcu}}
 
+# Custom build options
+build.opt.name=build_opt.h
+build.opt.path={build.path}/{build.opt.name}
+
 # Check if custom partitions exist: source > variant > build.partitions
 recipe.hooks.prebuild.1.pattern=bash -c "[ ! -f "{build.source.path}"/partitions.csv ] || cp -f "{build.source.path}"/partitions.csv "{build.path}"/partitions.csv"
 recipe.hooks.prebuild.2.pattern=bash -c "[ -f "{build.path}"/partitions.csv ] || [ ! -f "{build.variant.path}"/partitions.csv ] || cp "{build.variant.path}"/partitions.csv "{build.path}"/partitions.csv"
@@ -124,14 +128,21 @@ recipe.hooks.prebuild.3.pattern.windows=cmd /c if not exist "{build.path}\partit
 recipe.hooks.prebuild.4.pattern=bash -c "[ -f "{build.source.path}"/bootloader.bin ] && cp -f "{build.source.path}"/bootloader.bin "{build.path}"/{build.project_name}.bootloader.bin || ( [ -f "{build.variant.path}"/bootloader.bin ] && cp "{build.variant.path}"/bootloader.bin "{build.path}"/{build.project_name}.bootloader.bin || cp -f "{runtime.platform.path}"/tools/sdk/{build.mcu}/bin/bootloader_{build.boot}_{build.flash_freq}.bin "{build.path}"/{build.project_name}.bootloader.bin )"
 recipe.hooks.prebuild.4.pattern.windows=cmd /c IF EXIST "{build.source.path}\bootloader.bin" ( COPY /y "{build.source.path}\bootloader.bin" "{build.path}\{build.project_name}.bootloader.bin" ) ELSE ( IF EXIST "{build.variant.path}\bootloader.bin" ( COPY "{build.variant.path}\bootloader.bin" "{build.path}\{build.project_name}.bootloader.bin" ) ELSE ( COPY /y "{runtime.platform.path}\tools\sdk\{build.mcu}\bin\bootloader_{build.boot}_{build.flash_freq}.bin" "{build.path}\{build.project_name}.bootloader.bin" ) )
 
+# Check if custom build options exist in the sketch folder
+recipe.hooks.prebuild.5.pattern=bash -c "[ ! -f "{build.source.path}"/build_opt.h ] || cp -f "{build.source.path}"/build_opt.h "{build.path}"/build_opt.h"
+recipe.hooks.prebuild.6.pattern=bash -c "[ -f "{build.path}"/build_opt.h ] || touch "{build.path}"/build_opt.h"
+
+recipe.hooks.prebuild.5.pattern.windows=cmd /c if exist "{build.source.path}\build_opt.h" COPY /y "{build.source.path}\build_opt.h" "{build.path}\build_opt.h"
+recipe.hooks.prebuild.6.pattern.windows=cmd /c if not exist "{build.path}\build_opt.h" type nul > "{build.path}\build_opt.h"
+
 ## Compile c files
-recipe.c.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.cpreprocessor.flags} {compiler.c.flags} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} -DARDUINO_BOARD="{build.board}" -DARDUINO_VARIANT="{build.variant}" {compiler.c.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}"
+recipe.c.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.cpreprocessor.flags} {compiler.c.flags} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} -DARDUINO_BOARD="{build.board}" -DARDUINO_VARIANT="{build.variant}" {compiler.c.extra_flags} {build.extra_flags} "@{build.opt.path}" {includes} "{source_file}" -o "{object_file}"
 
 ## Compile c++ files
-recipe.cpp.o.pattern="{compiler.path}{compiler.cpp.cmd}" {compiler.cpreprocessor.flags} {compiler.cpp.flags} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} -DARDUINO_BOARD="{build.board}" -DARDUINO_VARIANT="{build.variant}" {compiler.cpp.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}"
+recipe.cpp.o.pattern="{compiler.path}{compiler.cpp.cmd}" {compiler.cpreprocessor.flags} {compiler.cpp.flags} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} -DARDUINO_BOARD="{build.board}" -DARDUINO_VARIANT="{build.variant}" {compiler.cpp.extra_flags} {build.extra_flags} "@{build.opt.path}" {includes} "{source_file}" -o "{object_file}"
 
 ## Compile S files
-recipe.S.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.cpreprocessor.flags} {compiler.S.flags} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} -DARDUINO_BOARD="{build.board}" -DARDUINO_VARIANT="{build.variant}" {compiler.S.extra_flags} {build.extra_flags} {includes} "{source_file}" -o "{object_file}"
+recipe.S.o.pattern="{compiler.path}{compiler.c.cmd}" {compiler.cpreprocessor.flags} {compiler.S.flags} -DF_CPU={build.f_cpu} -DARDUINO={runtime.ide.version} -DARDUINO_{build.board} -DARDUINO_ARCH_{build.arch} -DARDUINO_BOARD="{build.board}" -DARDUINO_VARIANT="{build.variant}" {compiler.S.extra_flags} {build.extra_flags} "@{build.opt.path}" {includes} "{source_file}" -o "{object_file}"
 
 ## Create archives
 recipe.ar.pattern="{compiler.path}{compiler.ar.cmd}" {compiler.ar.flags} {compiler.ar.extra_flags} "{archive_file_path}" "{object_file}"