Minor but annoying qcc bug

[Conor Olive]

Hi all, 

Not sure if bugs in qcc should still be reported on sandbox/bugs since this one is primarily triggered through specific types of include paths (i.e. environment dependent rather than code dependent). Specifically the way that I triggered this was by compiling qcc inside of ~/mydomain.com, where the default include path (-DBASILISK=...) is baked into the binary, then trying to use qcc to compile any of the examples (e.g. karman.c). Seemingly this can also be reproduced by any of the parent folders in -DBASILISK=... containing *.c* or *.h* in the folder name. 

The offending LoC found is 481 in src/include.lex (is_code) which searches for .c/.h anywhere in the path string rather than just at the end. The obvious fix here is to simply look only at the end (or otherwise be very careful about the parent folders' naming).

The attached patch fixes this edge case. I would be happy to write a bug report in the sandbox if this is helpful.

Best regards,

Conor