Do not add quotes around flags argument

* build/soong will adds quotes around the whole flags
  and preserve the quotes around flags argument.
  The quotes incorrectly became part of a flag's value.
* now -warnings-as-errors= works and finds some warnings;
  allow those warnings until they are fixed in source files.

Bug: 180862582
Test: make; make with WITH_TIDY=1
Change-Id: Ida4d8b54bf4546d241333e4a0e6ab1002e346e6f
1 file changed