py/mkrules.mk: Add link to build troubleshooting on failure.

Also update the submodules help text to match.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

py/mkrules.mk

@@ -4,6 +4,9 @@ THIS_MAKEFILE = $(lastword $(MAKEFILE_LIST))
 include $(dir $(THIS_MAKEFILE))mkenv.mk
 endif
 
+HELP_BUILD_ERROR ?= "See \033[1;31mhttps://github.com/micropython/micropython/wiki/Build-Troubleshooting\033[0m"
+HELP_MPY_LIB_SUBMODULE ?= "\033[1;31mError: micropython-lib submodule is not initialized.\033[0m Run 'make submodules'"
+
 # Extra deps that need to happen before object compilation.
 OBJ_EXTRA_ORDER_DEPS =
 
@@ -53,7 +56,7 @@ $(BUILD)/%.o: %.s
 
 define compile_c
 $(ECHO) "CC $<"
-$(Q)$(CC) $(CFLAGS) -c -MD -o $@ $<
+$(Q)$(CC) $(CFLAGS) -c -MD -o $@ $< || (echo -e $(HELP_BUILD_ERROR); false)
 @# The following fixes the dependency file.
 @# See http://make.paulandlesley.org/autodep.html for details.
 @# Regex adjusted from the above to play better with Windows paths, etc.
@@ -65,7 +68,7 @@ endef
 
 define compile_cxx
 $(ECHO) "CXX $<"
-$(Q)$(CXX) $(CXXFLAGS) -c -MD -o $@ $<
+$(Q)$(CXX) $(CXXFLAGS) -c -MD -o $@ $< || (echo -e $(HELP_BUILD_ERROR); false)
 @# The following fixes the dependency file.
 @# See http://make.paulandlesley.org/autodep.html for details.
 @# Regex adjusted from the above to play better with Windows paths, etc.
@@ -182,7 +185,7 @@ endif
 
 # to build frozen_content.c from a manifest
 $(BUILD)/frozen_content.c: FORCE $(BUILD)/genhdr/qstrdefs.generated.h $(BUILD)/genhdr/root_pointers.h | $(MICROPY_MPYCROSS_DEPENDENCY)
-	$(Q)test -e "$(MPY_LIB_DIR)/README.md" || (echo "Error: micropython-lib not initialized. Run 'make submodules'"; false)
+	$(Q)test -e "$(MPY_LIB_DIR)/README.md" || (echo -e $(HELP_MPY_LIB_SUBMODULE); false)
 	$(Q)$(MAKE_MANIFEST) -o $@ -v "MPY_DIR=$(TOP)" -v "MPY_LIB_DIR=$(MPY_LIB_DIR)" -v "PORT_DIR=$(shell pwd)" -v "BOARD_DIR=$(BOARD_DIR)" -b "$(BUILD)" $(if $(MPY_CROSS_FLAGS),-f"$(MPY_CROSS_FLAGS)",) --mpy-tool-flags="$(MPY_TOOL_FLAGS)" $(FROZEN_MANIFEST)
 endif