The "invalid" output file in metadata file when also doing linking

[vojkan99]

In the implementation of the metadata feature, the output file is derived from -o option, if specified. In case when GCC also calls linker after compiling, the -o option specifies the final executable. Therefore, GCC (as well as GNU ld) take the final executable to be the output file in its metadata files. If both GCC and GNU ld put metadata files in the same place, the GCC metadata file will overwrite GNU ld metadata file as they are both named the same, with the gitoid of the IM.