CMake; windows: link to lowercase 'shlwapi' - consistent with headers (#840)
CMake; windows: link to lowercase 'shlwapi' - consistent with headers (#840)

The filenames are consistently inconsistent in windows world, might
have something to do with default file system being case-insensitive.
While the native MinGW buils were fixed in 52613079824ac58d06c070aa9fbbb186a5859e2c
that only addressed the headers, but not libraries.
The problem remains when one tries to do a MinGW cross-build from
case-sensitive filesystem.
google/benchmark,mockingbirdnest/benchmark,mockingbirdnest/benchmark,mockingbirdnest/benchmark,mockingbirdnest/benchmark,google/benchmark,google/benchmark