build: Redid this thing in sed to make it work on more platforms.

GNUmakefile

@@ -7,8 +7,8 @@ MAKEFLAGS += --no-builtin-rules
 ##
 ## This is a list of all supported build targets.
 ##
-## Note: Consider passing -j$(nproc) or adding it to your $MAKEFLAGS to build
-## in parallel (faster).
+## Consider passing -j$(nproc) or adding it to your $MAKEFLAGS to build in
+## parallel (faster).
 ##
 ## Useful variables to override:
 ##    CC            Compiler.
@@ -1245,12 +1245,10 @@ clean: ## Clean all generated files from the out/ directory.
 ## Documentation:
 ##
 help: ## Display this help message.
-	@gawk -vG=$$(tput setaf 2) -vR=$$(tput sgr0) ' \
-		match($$0, "^(([^#:]*[^ :]) *:)?([^#]*)##([^#].+|)$$",a) { \
-			if (a[2] != "") { printf "    make %s%-22s%s %s\n", G, a[2], R, a[4]; next }\
-			if (a[3] == "") { print a[4]; next }\
-			printf "\n%-36s %s\n","",a[4]\
-		}' $(filter-out %.d,$(MAKEFILE_LIST))
+	@awk -F: ' \
+	/^##/ { sub(/^##\s?/, ""); print $$0 } \
+	/^\w+: .*##/ { sub(/^/, ""); sub(/:.*##\s?/, ":"); printf "%-32s %s\n", $$1, $$2 } \
+	' < $(filter-out %.d,$(MAKEFILE_LIST))
 	@echo "" # Blank line.
 .PHONY: help
 .DEFAULT_GOAL := help