Makefile: Properly resolve conflict from 4.9.145

Commit 4c219af48b1e ("kbuild: allow to use GCC toolchain not in Clang
search path") was not fully applied because of a conflict with commit
4dcb0afde6f4 ("ANDROID: Kbuild, LLVMLinux: allow overriding clang target
triple").

Change-Id: Ifbea30c010fb44decff10dd3d565eebfbfcbb005
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
diff --git a/Makefile b/Makefile
index d1de131..b72a28c 100644
--- a/Makefile
+++ b/Makefile
@@ -517,7 +517,9 @@
 ifeq ($(shell $(srctree)/scripts/clang-android.sh $(CC) $(CLANG_TARGET)), y)
 $(error "Clang with Android --target detected. Did you specify CLANG_TRIPLE?")
 endif
-GCC_TOOLCHAIN	:= $(realpath $(dir $(shell which $(LD)))/..)
+GCC_TOOLCHAIN_DIR := $(dir $(shell which $(LD)))
+CLANG_PREFIX	:= --prefix=$(GCC_TOOLCHAIN_DIR)
+GCC_TOOLCHAIN	:= $(realpath $(GCC_TOOLCHAIN_DIR)/..)
 endif
 ifneq ($(GCC_TOOLCHAIN),)
 CLANG_GCC_TC	:= --gcc-toolchain=$(GCC_TOOLCHAIN)