K 10
svn:author
V 8
bdrewery
K 8
svn:date
V 27
2017-04-13T22:07:34.987216Z
K 7
svn:log
V 2075
Cache compiler metadata and reuse it at installworld time.

Right after cross-tools, a compiler-metadata.mk file is created that
stores all of the bsd.compiler.mk metadata.  It is then read in
with a fail-safe during installworld time.

The file is explicitly removed when invoking cross-tools to ensure that
a stale file is not left around from odd manual 'make _cross-tools' ->
'make installworld' invocations.

This fixes several issues:
    - With WITH_SYSTEM_COMPILER (default yes on head and no on releng/11.0):
      If you build on a system where the bootstrap compiler does not
      build due to the host compiler matching the in-tree one, but then
      installworld on another system where that logic fails (a
      bootstrap compiler is needed), the installworld immediately fails
      with:
           sh: cc: not found
      Note that fixing this logic may then hit a case where a rebuild is
      attempted in installworld.  Normally cc would be ran with
      'CFLAGS+=ERROR-tried-to-rebuild-during-make-install' to cause an
      error such as:
          cc: error: no such file or directory: 'ERROR-tried-to-rebuild-during-make-install'
      However, now it will just fail with the 'cc: not found' error.
      Inspection of the compile line will show
      'ERROR-tried-to-rebuild-during-make-install';  It's not useful to
      set CC to anything other than 'cc' during install as it is more
      helpful to see the attempted compile rather than some other bogus
      error.
    - This now avoids running bsd.compiler.mk (cc executions) even more
      during installworld.  There are compiler-dependent SUBDIR in the
      tree which required having a compiler during install.

There is at least 1 case where CC is still executed in the install,
such as from a LOOKUP!= in secure/lib/libcrypto/Makefile.inc checking
for 'vzeroall' support.  This is not significant for installworld
as the lookup has a fallback (and hides its error) and only modifies CFLAGS,
thus it's not worth fixing.

PR:		212877
MFC after:	2 weeks
Sponsored by:	Dell EMC Isilon

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