Lots more unit tests and code cleanup
Relevant changes from ChangeLog
o job.c: Print -de error information when running multiple jobs
o var.c: only report error for unmatched regex subexpression
when linting (-dL) since we cannot tell when an unmatched
subexpression is an expected result.
reduce memory allocations in the modifiers ':D' and ':U'
reduce memory allocation and strlen calls in modifier ':from=to'
in the ':Q' modifier, only allocate memory if necessary
improve performance for LazyBuf
reduce debug logging and memory allocation for ${:U...}
reduce verbosity of the -dv debug logging for standard cases
fix double varname expansion in the variable modifier '::='
o var.c: avoid evaluating many modifiers in parse only mode
in strict mode (-dL) many variable references are parsed twice,
the first time just to report parse errors early, so we want to
avoid side effects and wasted effort to the extent possible.
Quite a lot of churn on style, but lots of
good work refactoring complicated functions
and lots more unit-tests.
Thanks mostly to rillig at NetBSD
Some interesting entries from ChangeLog
o .MAKE.{UID,GID} represent uid and gid running make.
o allow env var MAKE_OBJDIR_CHECK_WRITABLE=no to skip writable
checks in InitObjdir. Explicit .OBJDIR target always allows
read-only directory.
o add more unit tests for META MODE
Change-Id: I4d3bcf08b4c864d98b343f602efe5a75dbfa7a94
