Rust: fix MSVC-built lib pulling in other lib files

Author: angelsl

lib/builtins/CMakeLists.txt

@@ -361,11 +361,18 @@ else ()
         endif ()
       endforeach ()
 
+      # Rust: don't insert a reference to MSVCRT.lib/etc
+      if (MSVC)
+        set(_cflags -Zl)
+      else ()
+        set(_cflags -std=c99)
+      endif ()
+
       add_compiler_rt_runtime(clang_rt.builtins
                               STATIC
                               ARCHS ${arch}
                               SOURCES ${${arch}_SOURCES}
-                              CFLAGS "-std=c99"
+                              CFLAGS ${_cflags}
                               PARENT_TARGET builtins)
     endif ()
   endforeach ()

lib/builtins/int_math.h

@@ -28,7 +28,9 @@
 #if defined(_MSC_VER) && !defined(__clang__)
 #include <math.h>
 #include <stdlib.h>
-#include <ymath.h>
+// Rust: need to upstream this
+// don't include ymath.h, it's not needed + pulls in the C++ stdlib for some reason
+// #include <ymath.h>
 #endif
 
 #if defined(_MSC_VER) && !defined(__clang__)