[jdk8u-dev] RFR: 8374948: [8u] saproc & jsig builds add duplicate linker flags on Darwin/MacOS [v4]

[Andrew John Hughes]

> This patch breaks out the Mac minimum version argument into its own variable, `MAC_FLAGS`, in `gcc.make`, so it can be added independently in `saproc.make` and `jsig.make`. This prevents duplicate linker flags and C++-only flags being added to the C build for jsig and saproc.

Andrew John Hughes has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains eight commits:

 - Merge remote-tracking branch 'dev/master' into JDK-8374948
 - Revert LOG_LEVEL=debug additions
 - 8374948: [8u] saproc & jsig builds add duplicate linker flags on Darwin/MacOS
 - Backport 1b0f612e5e08cfa1581cf22433b36b5f075c0f23
 - Print spec files on all POSIX platforms
 - Add LOG_LEVEL=debug to all GHA builds
 - Whitespace cleanup
 - 8374899: [8u] Fully handle clang as the toolchain in flags.m4

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Changes: https://git.openjdk.org/jdk8u-dev/pull/742/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk8u-dev&pr=742&range=03
  Stats: 13 lines in 4 files changed: 2 ins; 1 del; 10 mod
  Patch: https://git.openjdk.org/jdk8u-dev/pull/742.diff
  Fetch: git fetch https://git.openjdk.org/jdk8u-dev.git pull/742/head:pull/742

PR: https://git.openjdk.org/jdk8u-dev/pull/742