Hi,

the current $global_symbol_pipe for 'MS dumpbin' yields symbol names starting with @ or ? on purpose.

As these symbol names are not valid C symbol names, this breaks following test cases with 64bit MSVC compiler, and even with 32bit since MSVC 14 (=VS 2015):

 27: link against a preloaded static library
 28: build and dynamically load a module
 29: preload static and dynamic module
 31: disable fast install
 32: force PIC objects
 34: hardcoding library path
 36: uninstalled libraries have priority
 37: linking with long file names

Attached patches does fix these test cases for 64bit MSVC (tested 10.0, 12.0, 14.0, 15.0) as well as for 32bit MSVC 14.0 and 15.0 (=VS 2017), in that it does accept only valid C symbol names for ltdl preloading.

Thanks!
/haubi/