[profile] Don't use pragma comment linker on mingw

At least when compiling with gcc, this is not supported and will
result in errors when linking against the profiler runtime. Only
use the pragma comment linker based code with MSVC, but not with
a mingw toolchain. This also undoes D107620, which shouldn't be
relevant anymore.

Differential Revision: https://reviews.llvm.org/D108095