git-extra: fix build with clangarm64

To make `-D__USE_MINGW_ANSI_STDIO=1` work (which is implicitly set via
`/etc/makepkg_mingw.conf`), with clangarm64 we need to link to
libmsvcrt-os. Otherwise the build would fail with:

  ld.lld: error: undefined symbol: __ms_printf
  [...]
  ld.lld: error: undefined symbol: __ms_sscanf

With toolchains other than `clangarm64`, linking to that static library
does not hurt, so let's do it unconditionally.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

git-extra/Makefile

@@ -21,7 +21,7 @@ $(BUILDDIR)/%.res: $(SRCDIR)/%.rc
 	$(WINDRES) --input $< --output $@ --output-format coff
 
 $(BUILDDIR)/WhoUses.exe: $(BUILDDIR)/WhoUses.o $(BUILDDIR)/SystemInfo.o
-	$(CXX) $(CXXFLAGS) -o $@ $(LDFLAGS) $^
+	$(CXX) $(CXXFLAGS) -o $@ $(LDFLAGS) $^ -lmsvcrt-os
 
 $(BUILDDIR)/WhoUses.o: $(SRCDIR)/WhoUses.cpp $(SRCDIR)/SystemInfo.h
 $(BUILDDIR)/SystemInfo.o: $(SRCDIR)/SystemInfo.cpp $(SRCDIR)/SystemInfo.h