Remove consecutive platform defines

Generated code must macro-guard platform specific code, but did it in a
naive fashion where consecutive guards for the same platform repeated the
macro. With the help of PlatformGuardHelper, the code generation will elide
redundant macro guards.

scripts/generators/generator_utils.py

@@ -0,0 +1,25 @@
+#!/usr/bin/python3 -i
+#
+# Copyright 2023 The Khronos Group Inc.
+# Copyright 2023 Valve Corporation
+# Copyright 2023 LunarG, Inc.
+# Copyright 2023 RasterGrid Kft.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+class PlatformGuardHelper():
+    """Used to elide platform guards together, so redundant #endif then #ifdefs are removed
+    Note - be sure to call addGuard(None) when done to add a trailing #endif if needed
+    """
+    def __init__(self):
+        self.currentGuard = None
+
+    def addGuard(self, guard):
+        out = []
+        if self.currentGuard != guard:
+            if self.currentGuard != None:
+                out.append(f'#endif  // {self.currentGuard}\n')
+            if guard != None:
+                out.append(f'#ifdef {guard}\n')
+            self.currentGuard = guard
+        return out