openbsd: use specific linker for building

By default, rustc use `cc` as linker. Under OpenBSD, `cc` is gcc version 4.2.1.
So use the compiler found at configure-time for linking: it will be gcc 4.9.

It permits to resolv problem of finding -lestdc++ or -lgcc. For base gcc (4.2), there are in not standard path, whereas for ports gcc (4.9) there are in standard path.

Author: semarie

mk/cfg/x86_64-unknown-openbsd.mk

@@ -20,3 +20,4 @@ CFG_LDPATH_x86_64-unknown-openbsd :=
 CFG_RUN_x86_64-unknown-openbsd=$(2)
 CFG_RUN_TARG_x86_64-unknown-openbsd=$(call CFG_RUN_x86_64-unknown-openbsd,,$(2))
 CFG_GNU_TRIPLE_x86_64-unknown-openbsd := x86_64-unknown-openbsd
+RUSTC_FLAGS_x86_64-unknown-openbsd=-C linker=$(call FIND_COMPILER,$(CC))

src/test/run-make/tools.mk

@@ -85,6 +85,7 @@ ifeq ($(UNAME),Bitrig)
 else
 ifeq ($(UNAME),OpenBSD)
 	EXTRACFLAGS := -lm -lpthread
+	RUSTC := $(RUSTC) -C linker="$(word 1,$(CC:ccache=))"
 else
 	EXTRACFLAGS := -lm -lrt -ldl -lpthread
 	EXTRACXXFLAGS := -lstdc++