mk/rt/jemalloc: pass CFG_GCCISH_CFLAGS inside CC instead of passing C…

…FG_CFLAGS in EXTRA_CFLAGS

 - CFG_CFLAGS is gone (it was previously only used by jemalloc anyhow).
 - CFG_JEMALLOC_CFLAGS may contain flags needed for the compiler to
   function (produce a binary output).
 - jemalloc's configure runs $(CC) without EXTRA_CFLAGS, and (without
   this change) will fail if any flags are required for CC to work.

mk/rt.mk

@@ -177,11 +177,11 @@ $$(JEMALLOC_LOCAL_$(1)): $$(JEMALLOC_DEPS) $$(MKFILE_DEPS)
 	cd "$$(JEMALLOC_BUILD_DIR_$(1))"; "$(S)src/jemalloc/configure" \
 		$$(JEMALLOC_ARGS_$(1)) --with-jemalloc-prefix=je_ $(CFG_JEMALLOC_FLAGS) \
 		--build=$$(CFG_GNU_TRIPLE_$(CFG_BUILD)) --host=$$(CFG_GNU_TRIPLE_$(1)) \
-		CC="$$(CC_$(1))" \
+		CC="$$(CC_$(1)) $$(CFG_JEMALLOC_CFLAGS_$(1))" \
 		AR="$$(AR_$(1))" \
 		RANLIB="$$(AR_$(1)) s" \
 		CPPFLAGS="-I $(S)src/rt/" \
-		EXTRA_CFLAGS="$$(CFG_CFLAGS_$(1)) $$(CFG_JEMALLOC_CFLAGS_$(1)) -g1"
+		EXTRA_CFLAGS="-g1"
 	$$(Q)$$(MAKE) -C "$$(JEMALLOC_BUILD_DIR_$(1))" build_lib_static
 
 ifeq ($$(CFG_DISABLE_JEMALLOC),)