FROMLIST: Makefile: lld: tell clang to use lld

This is needed because clang doesn't select which linker to use based on
$LD but rather -fuse-ld=lld. This is problematic especially for
cc-ldoption, which checks for linker flag support via invoking the
compiler, rather than the linker.

(am from https://lkml.org/lkml/2019/2/11/1947)

Link: ClangBuiltLinux/linux#342
Suggested-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Bug: 63740206
Change-Id: I3edf2f0f6c0bac842bef22194bd48a993fc0e3c0
Signed-off-by: Yousef Algadri <yusufgadrie@gmail.com>
Signed-off-by: Raphiel Rollerscaperers <rapherion@raphielgang.org>

Makefile

@@ -630,6 +630,9 @@ CLANG_FLAGS    += $(call cc-option, -Wno-bool-operation)
 CLANG_FLAGS    += $(call cc-option, -Wno-string-concatenation)
 KBUILD_CFLAGS	+= $(CLANG_FLAGS)
 KBUILD_AFLAGS	+= $(CLANG_FLAGS)
+ifeq ($(ld-name),lld)
+KBUILD_CFLAGS	+= -fuse-ld=lld
+endif
 export CLANG_FLAGS
 endif