esp32/mpconfigport: Enable the RV32 emitter for ESP32C3 targets.

The RV32 code emitter assumed that the arch-specific NLR was used
instead of the setjmp/longjmp based NLR code.  If the latter NLR
provider was chosen, the emitter would allocate space on the stack
for the NLR buffer but would not fill it in.

This change turns off setjmp()-based NLR and GCREGS for the ESP32C3
target, in favour of more platform-tailored alternatives.  As setjmp()
NLR is now disabled by default, the RV32 emitter can be safely enabled
by default as well for the target in question.
Signed-off-by: Alessandro Gatti <a.gatti@frob.it>

ports/esp32/mpconfigport.h

@@ -18,9 +18,8 @@
 
 // object representation and NLR handling
 #define MICROPY_OBJ_REPR                    (MICROPY_OBJ_REPR_A)
+#if !CONFIG_IDF_TARGET_ESP32C3
 #define MICROPY_NLR_SETJMP                  (1)
-#if CONFIG_IDF_TARGET_ESP32C3
-#define MICROPY_GCREGS_SETJMP               (1)
 #endif
 
 // memory allocation policies
@@ -44,6 +43,8 @@
 #define MICROPY_PERSISTENT_CODE_LOAD        (1)
 #if !CONFIG_IDF_TARGET_ESP32C3
 #define MICROPY_EMIT_XTENSAWIN              (1)
+#else
+#define MICROPY_EMIT_RV32                   (1)
 #endif
 
 // workaround for xtensa-esp32-elf-gcc esp-2020r3, which can generate wrong code for loops