Disable -Werror in debug builds

build/Makefile

@@ -1,4 +1,4 @@
-all: gba_build native_build native_debug_build windows_release windows_debug
+all: gba_build gba_debug_build native_build native_debug_build windows_release windows_debug
 
 MAKE=make -j
 
@@ -7,6 +7,11 @@ gba_build:
 		${MAKE} -C gba-release ${ARGS}; \
 	fi
 
+gba_debug_build:
+	@if [ -d gba-debug ]; then \
+		${MAKE} -C gba-debug ${ARGS}; \
+	fi
+
 native_build:
 	@if [ -d ${HOST_ENV}-release ]; then \
 		${MAKE} -C ${HOST_ENV}-release ${ARGS}; \