Define __RGBDS_VERSION__ as the output of rgbasm --version (sans "rgbasm")

Fixes #824

test/asm/test.sh

@@ -38,12 +38,14 @@ tryCmp () {
 
 # Add the version constants test, outputting the closest tag to the HEAD
 if git describe --tags --abbrev=0 > version.out; then
+	$RGBASM --version >> version.out
 	cat > version.asm <<EOF
 IF !DEF(__RGBDS_RC__)
 	PRINTLN "v{d:__RGBDS_MAJOR__}.{d:__RGBDS_MINOR__}.{d:__RGBDS_PATCH__}"
 ELSE
 	PRINTLN "v{d:__RGBDS_MAJOR__}.{d:__RGBDS_MINOR__}.{d:__RGBDS_PATCH__}-rc{d:__RGBDS_RC__}"
 ENDC
+	PRINTLN "rgbasm {__RGBDS_VERSION__}"
 EOF
 else
 	echo "${bold}${orange}Warning: cannot run version test!${rescolors}${resbold}"