Fix clang build if CC is not in the path.

If CC points to clang the linker was set to ld.lld. Copy the diectory
name from CC is it has one.

Change-Id: I50aef5dddee4d2540b12b6d4e68068ad004446f7
Signed-off-by: Arve Hjønnevåg <arve@android.com>

Makefile

@@ -207,9 +207,10 @@ AS			=	$(CC) -c -x assembler-with-cpp $(TF_CFLAGS_$(ARCH))
 CPP			=	$(CC) -E $(TF_CFLAGS_$(ARCH))
 PP			=	$(CC) -E $(TF_CFLAGS_$(ARCH))
 else ifneq ($(findstring clang,$(notdir $(CC))),)
+CLANG_CCDIR		=	$(if $(filter-out ./,$(dir $(CC))),$(dir $(CC)),)
 TF_CFLAGS_aarch32	=	$(target32-directive) $(march32-directive)
 TF_CFLAGS_aarch64	=	-target aarch64-elf $(march64-directive)
-LD			=	ld.lld
+LD			=	$(CLANG_CCDIR)ld.lld
 ifeq (, $(shell which $(LD)))
 $(error "No $(LD) in PATH, make sure it is installed or set LD to a different linker")
 endif