In Microsoft mode(-fms-compatibility), prefer an integral conversion to a floating...

In Microsoft mode(-fms-compatibility), prefer an integral conversion to a floating-to-integral conversion if the integral conversion is between types of the same size.

For example:
 void f(float);
 void f(int);
 int main {
    long a;
    f(a);
 }
Here, MSVC will call f(int) instead of generating a compile error as clang will do in standard mode.
This fixes a few errors when parsing MFC code with clang.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@140007 91177308-0d34-0410-b5e6-96231b3b80d8