Add IL compat flag to Windows builds, see microsoft/php-sdk-binary-tools#72

Author: dwgebler

win32/build/config.w32

@@ -130,6 +130,11 @@ ADD_FLAG("ARFLAGS", '/nologo /libpath:"' + php_usual_lib_suspects + '" ');
 probe_basic_headers();
 add_extra_dirs();
 
+// Allow compatible IL versions, do not require an exact match.
+// Prevents build failures where different libs were built with different (but compatible) IL versions.
+// See fatal error C1047.
+ADD_FLAG("LDFLAGS", "/d2:-AllowCompatibleILVersions ");
+
 //DEFINE("PHP_BUILD", PHP_PHP_BUILD);
 
 ARG_WITH("analyzer", "Enable static analyzer. Pass vs for Visual Studio, clang for clang, cppcheck for Cppcheck, pvs for PVS-Studio", "no");