ANDROID: kbuild: disable clang-specific configs with other compilers

cuttlefish_defconfig explicitly enables options that fail to compile
with compilers other than clang. This change detects when a different
compiler is used and disables clang-specific features after printing
a warning.

Bug: 145297810
Change-Id: I3371576b45c9715a63c5668ab58e996cab612f53
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>