Merge #19203

19203: make: pass make jobserver to cargo r=kaspar030 a=kaspar030



Co-authored-by: Kaspar Schleiser <kaspar@schleiser.de>

makefiles/cargo-targets.inc.mk

@@ -59,7 +59,8 @@ $(CARGO_LIB): $(RIOTBUILD_CONFIG_HEADER_C) $(BUILDDEPS) $(CARGO_COMPILE_COMMANDS
 		($(COLOR_ECHO) \
 		'$(COLOR_RED)Error: No Rust libraries are installed for the board'"'"'s CPU.$(COLOR_RESET) Run\n    $(COLOR_GREEN)$$$(COLOR_RESET) rustup target add $(RUST_TARGET) $(patsubst %,--toolchain %,$(CARGO_CHANNEL))\nor set `CARGO_OPTIONS=-Zbuild-std=core`.'; \
 		exit 1)
-	$(Q)CC= CFLAGS= CPPFLAGS= CXXFLAGS= \
+	$(Q)# finally call out to cargo. mind the "+" to pass down make's jobserver.
+	$(Q)+ CC= CFLAGS= CPPFLAGS= CXXFLAGS= \
 		RIOT_COMPILE_COMMANDS_JSON="$(CARGO_COMPILE_COMMANDS)" \
 		RIOT_USEMODULE="$(USEMODULE)" \
 		cargo $(patsubst +,,+${CARGO_CHANNEL}) \