8371914: PNG defines in CFLAGS can cause compilation errors with external libpng

[bsdkurt]

When building with external libpng the PNG defines added to CFLAGS may conflict with the installed libpng header pnglibconf.h resulting in compilation errors. For example on OpenBSD/aarch64:

/usr/local/include/pnglibconf.h:207:9: error: 'PNG_ARM_NEON_OPT' macro redefined [-Werror,-Wmacro-redefined]

This moves all -DPNG_* into the case where internal libpng is used. This has only been tested with the tier1 github actions so needs to be checked on Linux/ppc and AIX.

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Progress

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Issue

• JDK-8371914: PNG defines in CFLAGS can cause compilation errors with external libpng (Bug - P4)

Reviewers

• Erik Joelsson (@erikj79 - Reviewer)

Reviewing

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[bridgekeeper]

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[openjdk]

@bsdkurt This change is no longer ready for integration - check the PR body for details.

[openjdk]

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[mlbridge]

Webrevs

• 00: Full (a7c9813f)

[erikj79]

I think this looks ok, but someone from client should weigh in too.

/reviewers 2

[openjdk]

@erikj79
The total number of required reviews for this PR (including the jcheck configuration and the last /reviewers command) is now set to 2 (with at least 1 Reviewer, 1 Author).