BACKPORT: tools: Factor HOSTCC, HOSTLD, HOSTAR definitions

Several Makefiles in tools/ need to define the host toolchain variables.
Move their definition to tools/scripts/Makefile.include

Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://lore.kernel.org/bpf/20201110164310.2600671-2-jean-philippe@linaro.org
(cherry picked from commit c8a950d0d3b926a02c7b2e713850d38217cec3d1)
Bug: 145210207
Signed-off-by: Alistair Delva <adelva@google.com>
Change-Id: Ia2694f0afb5546d9d118e77425fb3dc1eaece07a

tools/objtool/Makefile

@@ -3,15 +3,6 @@ include ../scripts/Makefile.include
 include ../scripts/Makefile.arch
 
 # always use the host compiler
-ifneq ($(LLVM),)
-HOSTAR	?= llvm-ar
-HOSTCC	?= clang
-HOSTLD	?= ld.lld
-else
-HOSTAR	?= ar
-HOSTCC	?= gcc
-HOSTLD	?= ld
-endif
 AR	 = $(HOSTAR)
 CC	 = $(HOSTCC)
 LD	 = $(HOSTLD)