Add flag property checking

Some checks for common errors with user-provided compiler and linker

* Using -I instead of include_dirs
* Using -l<lib> in ldflags instead of host_ldlibs (or shared_libs)
* Using -L in ldflags
* Splitting a multi-word flag into two flags
* Combining two flags into one list entry
* Using a path that could search outside the source or output trees
* Using a non-whitelisted library in host_ldlibs

Maybe some of the flag checks should happen during a static analysis
pass, but we don't have one right now, and this only adds ~1/2 second to
our 73 second Mega_device runs (recompile the changed code, run
soong_build, then report unknown target).

Change-Id: Icea7436260f1caa62c0cec29817a1cfea27b3e7c
7 files changed