RFR: 8278163: --with-cacerts-src variable resolved after GenerateCacerts recipe setup

[Andrew Leonard]

PR https://github.com/openjdk/jdk/pull/6647 resolved the GENDATA_CACERTS_SRC fir --with-cacerts-src after the recipe, which meant the dependencies were wrong.
This PR moves it before the recipe.

Signed-off-by: Andrew Leonard <anleonar at redhat.com>

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Commit messages:
 - 8278163: --with-cacerts-src variable resolved after GenerateCacerts recipe setup

Changes: https://git.openjdk.java.net/jdk/pull/6680/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6680&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8278163
  Stats: 8 lines in 1 file changed: 4 ins; 3 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6680.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6680/head:pull/6680

PR: https://git.openjdk.java.net/jdk/pull/6680