Martin Storsjö authored Jul 23, 2018 and Hugo Beauzée-Luyssen committed Sep 28, 2018

GCC supports using a custom spec file to override the default rules
of linking in -lmsvcrt and -lkernel32 etc.

Clang doesn't support spec files. But the mingw target in clang
recognizes certain libraries (-lmsvcr* and -lucrt*, and -lwindowsapp)
and will omit the corresponding default library rules if these are
found. And since llvm-mingw uses lld for linking, which is less picky
about the exact order of library flags than binutils ld, adding these
libraries in EXTRA_LDFLAGS works just fine for this case.

Signed-off-by: Hugo Beauzée-Luyssen <hugo@beauzee.fr>