scanner: Make shlib Resolution Work Also With Visual C++

Commit f3fcdf97 introduced shlib resolution for Windows, but it only works
with MinGW and would therefore break builds of introspection files for
Visual C++.

Improve on the situation by adding capabilities to do the same with Visual
C++, as the introspection dumper program is still compiled and linked with
the Microsoft tool set (only the proprocessor to process the various
headers is using GCC/MinGW).

This makes use of the dumpbin utility that is shipped with Visual C++,
which will query a .lib file, which leads to the DLL that the .lib file
will link to.  The 'gcc -print-search-dirs' can be replaced on Visual C++
builds by querying the LIB environment variable, as this is what the Visual
C++ compiler/linker really looks at during compilation and linkage.

https://bugzilla.gnome.org/show_bug.cgi?id=724890
MSVC Builds: Update Introspection Build Process

The introspection build on Windows recently received support to deduce the
DLL name from the library that is passed into g-ir-scanner, so the library
name (without the file name extensions, etc) ought to be passed in for the
build of introspection files on Windows, just like the *nix builds of
g-i.