Bypass `version.h` checks when running include-what-you-use

Signed-off-by: Michael Richters <gedankenexperimenter@gmail.com>

src/kaleidoscope/version.h

@@ -1,5 +1,12 @@
+// -*- mode: c++ -*-
+
 #pragma once
 
+// We use `include-what-you-use`, which uses `clang` to help manage header
+// includes.  If we don't guard this file with an #ifdef, it will cause that to
+// fail on any file that includes this header.
+#ifndef __clang__
+
 #define KALEIDOSCOPE_AVR_GCC_MINIMAL_VERSION 5
 #define KALEIDOSCOPE_AVR_GCC_MINIMAL_MINOR 4
 
@@ -9,3 +16,5 @@
       )
 #error Kaleidoscope requires Arduino version >= 1.8.6 to build. Please upgrade.
 #endif
+
+#endif // #ifndef __clang__