selftests: fix LLVM build for i386 and x86_64

Add missing cases for the i386 and x86_64 architectures when
determining the LLVM target for building kselftest.

Fixes: 795285ef ("selftests: Fix clang cross compilation")
Signed-off-by: Guillaume Tucker <guillaume.tucker@collabora.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/lib.mk

@@ -10,12 +10,14 @@ endif
 CLANG_TARGET_FLAGS_arm          := arm-linux-gnueabi
 CLANG_TARGET_FLAGS_arm64        := aarch64-linux-gnu
 CLANG_TARGET_FLAGS_hexagon      := hexagon-linux-musl
+CLANG_TARGET_FLAGS_i386         := i386-linux-gnu
 CLANG_TARGET_FLAGS_m68k         := m68k-linux-gnu
 CLANG_TARGET_FLAGS_mips         := mipsel-linux-gnu
 CLANG_TARGET_FLAGS_powerpc      := powerpc64le-linux-gnu
 CLANG_TARGET_FLAGS_riscv        := riscv64-linux-gnu
 CLANG_TARGET_FLAGS_s390         := s390x-linux-gnu
 CLANG_TARGET_FLAGS_x86          := x86_64-linux-gnu
+CLANG_TARGET_FLAGS_x86_64       := x86_64-linux-gnu
 CLANG_TARGET_FLAGS              := $(CLANG_TARGET_FLAGS_$(ARCH))
 
 ifeq ($(CROSS_COMPILE),)