Making C++ header files results in uncleaned .gch files

[InfoTeddy]

This has been an issue when making .c and .cpp files before (see #314, #1268). Since then, it looks like -fsyntax-only was used (wherever possible) to prevent these files from being created. However, directly opening a header file and making it still results in .gch files being made.

#1268 (comment) suggests using -o /dev/null, but doing that makes the maker no longer work. In particular, glaring syntax errors in header files (like forgetting a semicolon) pass the maker just fine.

I am using the GCC maker.