scons: Have MinGW target MSVCRT 7.0

Necessary for _aligned_malloc/free().

scons/crossmingw.py

@@ -177,6 +177,7 @@ def generate(env):
     # default in recent gcc versions
     env.AppendUnique(CFLAGS = ['-gstabs'])
 
+    env.AppendUnique(CPPDEFINES = [('__MSVCRT_VERSION__', '0x0700')])
     #env.AppendUnique(LIBS = ['iberty'])
     env.AppendUnique(SHLINKFLAGS = ['-Wl,--enable-stdcall-fixup'])
     #env.AppendUnique(SHLINKFLAGS = ['-Wl,--kill-at'])