Foundation: build CoreFoundation as /MD

Use /MD and /MDd mode compilation rather than /MT or /MTd as per
Microsoft's recommendation.  This allows us to use a shared C runtime.
The static MSVCRT/ucrt cannot be intermingled with a dynamic one.

Author: compnerd

CMakeLists.txt

@@ -37,8 +37,9 @@ ExternalProject_Add(CoreFoundation
                       -DCMAKE_BUILD_TYPE=${CMAKE_BUILD_TYPE}
                       -DCMAKE_C_COMPILER=${CMAKE_C_COMPILER}
                       # NOTE(compnerd) ensure that we build it as a DLL as we
-                      # wish to re-export the symbols from Foundation
-                      -DCMAKE_C_FLAGS=-D_USRDLL
+                      # wish to re-export the symbols from Foundation.
+                      # Furthermore, build for the shared MSVCRT runtime.
+                      -DCMAKE_C_FLAGS="-D_USRDLL -D_DLL"
                       -DCMAKE_MAKE_PROGRAM=${CMAKE_MAKE_PROGRAM}
                       -DCMAKE_INSTALL_PREFIX=<INSTALL_DIR>
                       -DCMAKE_INSTALL_LIBDIR=usr/lib