[SwayamInSync]

A compiler error in a command line was printed and then ignored: the file was verified anyway, under different options than the ones given, and cpp-verify exited 0.

Input	Main	This change
header.h	error: invalid argument '-std=c++17' not allowed with 'C', then Verified, exit 0	Verified, exit 0
file.c	the same error, then Verified, exit 0	the error, not verified, exit 1
file.cpp -- -fbogus-flag	error: unknown argument, then Verified, exit 0	the error, not verified, exit 1
file.cpp -- -std=c++99	error: invalid value 'c++99', then Verified, exit 0	the error, not verified, exit 1

Clang's tooling reports driver and argument errors and goes on (ToolInvocation::run never checks them), where clang stops. cpp-verify now gives the tool a diagnostics consumer for those errors, and its action factory stops a file whose command line produced one; the frontend still reports with the file's own diagnostic options. A .h file is compiled as a C++ header, since clang takes it for C.

Testing: suite/input_errors.cpp fails on main; removing the header adjustment fails its header case, and letting a file with an argument error run fails the flag case. Verify suite: 398 passed, 1 unsupported.