MacOS.gcc_build_version: find GCC when unlinked

MacOS.gcc_42_build_version was returning nil if apple-gcc42 was
installed but unlinked, which was disjoint with how other parts of
Homebrew tried to see if it was present.
superenv: always respect HOMEBREW_CC

Closes #23322.
vim: patch for -no-cpp-precomp
OS::Mac: Add Xcode 2.5 compiler
ACE 6.2.2

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>
algol68g 2.8

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cloog 0.18.1

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cloog 0.18.1 bottles
curl 7.33.0

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dovecot 2.2.6

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ExifTool 9.39

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fping 3.6

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iso-codes 3.47

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LanguageTool 2.3

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libdiscid 0.6.1

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libmikmod 3.3.3

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libzdb 2.12

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mikmod 3.2.4

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MonetDB 11.15.17

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nagios-plugins 1.5

Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>