On MSVC, shared libraries only export symbols that have been explicitly exported
either as part of the symbol prototype or via a module definitions file.
On compilers other than MSVC, all symbols are exported in the shared library by
default and the format for the list of symbols to export is different, so this
is only used with the VisualStudio compiler.
The module defs file path can either be relative to the current source directory
or an absolute path using meson.source_root() + '/some/path'
This is very useful to prevent compiler noise about invalid cflags; particularly
for the -mms-bitfields cflag which most libraries send to the mingw-gcc
compiler. More can be added later.
Instead of checking if we're on Windows and not even trying, try to symlink and
if that fails due to insufficient privileges, then just continue. This allows
people who know what they're doing to allow users other than Administrators to
make symlinks on Windows, or allows them to just run Meson as an Administrator.
Jussi Pakkanen