UnitTestFrameworkPkg: Update to be more C11 compliant by using __func__

__FUNCTION__ is a pre-standard extension that gcc and Visual C++ among
others support, while __func__ was standardized in C99.

Since it's more standard, replace __FUNCTION__ with __func__ throughout
UnitTestFrameworkPkg.

Signed-off-by: Rebecca Cran <rebecca@bsdio.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>

UnitTestFrameworkPkg/Library/UnitTestLib/Log.c

@@ -118,7 +118,7 @@ UnitTestLogInit (
   // Make sure that you're cooking with gas.
   //
   if (Test == NULL) {
-    DEBUG ((DEBUG_ERROR, "%a called with invalid Test parameter\n", __FUNCTION__));
+    DEBUG ((DEBUG_ERROR, "%a called with invalid Test parameter\n", __func__));
     return;
   }