Make PROVIDE_xxx macro more robust

If symbold is defined into "1" then it could be used as
  #if PROVIDE_xxx
  ...
  #endif

That's what cland and gcc are using if -DPROVIDE_xxx is used on the
command-line:
  https://gcc.gnu.org/onlinedocs/gcc/Preprocessor-Options.html#index-D
  https://clang.llvm.org/docs/ClangCommandLineReference.html

Test: make

BUG=75971275

Change-Id: Idcb1eb05d1823d30a64049b1c079a8b4bd34946f