Merge branch 'win64-static-cpp' into 'master'

Link libstdc++ statically (avoid dependency)

See merge request !3

src/starsphere/Makefile.mingw

@@ -35,6 +35,7 @@ LIBS += -lboinc_graphics2 -lboinc_api -lboinc
 LIBS += -Wl,-Bdynamic
 LIBS += $(shell $(STARSPHERE_INSTALL)/bin/sdl2-config --static-libs)
 LIBS += -lopengl32 -lglu32
+LIBS += $(shell $(CXX) -print-file-name=libstdc++.a)
 
 LDFLAGS += -static-libgcc