RFR: 8298974: Add ftcolor.c to imported freetype sources

[Phil Race]

Add ftcolor.c to the freetype sources we import as it is needed for Emoji rendering.

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Commit messages:
 - 8298974

Changes: https://git.openjdk.org/jdk/pull/11728/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11728&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8298974
  Stats: 156 lines in 1 file changed: 156 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/11728.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11728/head:pull/11728

PR: https://git.openjdk.org/jdk/pull/11728