RFR: 8237770: Error creating fragment phong shader on iOS

[Jose Pereda]

This PR defines a pre-processor in the phong frag files to avoid inline declaration of #extension when several frags are combined that leads to the error:

syntax error: #extension must always be before any non-preprocessor tokens

-------------

Commits:
 - 14ccbe6a: Define pre-processor in frag files to avoid inline declaration of #extension when several frags are combined

Changes: https://git.openjdk.java.net/jfx/pull/93/files
 Webrev: https://webrevs.openjdk.java.net/jfx/93/webrev.00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8237770
  Stats: 45 lines in 15 files changed: 45 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jfx/pull/93.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/93/head:pull/93

PR: https://git.openjdk.java.net/jfx/pull/93