libpgcommon is a new static library to allow sharing code among the
various frontend programs and backend; this lets us eliminate duplicate
implementations of common routines. We avoid libpgport, because that's
intended as a place for porting issues; per discussion, it seems better
to keep them separate.
The first use case, and the only implemented by this patch, is pg_malloc
and friends, which many frontend programs were already using.
At the same time, we can use this to provide palloc emulation functions
for the frontend; this way, some palloc-using files in the backend can
also be used by the frontend cleanly. To do this, we change palloc() in
the backend to be a function instead of a macro on top of
MemoryContextAlloc(). This was previously believed to cause loss of
performance, but this implementation has been tweaked by Tom and Andres
so that on modern compilers it provides a slight improvement over the
previous one.
This lets us clean up some places that were already with
localized hacks.
Most of the pg_malloc/palloc changes in this patch were authored by
Andres Freund. Zoltán Böszörményi also independently provided a form of
that. libpgcommon infrastructure was authored by Álvaro.
Add errno-based output to error messages where appropriate, reformat
blocks to about 72 characters per line, use spaces instead of tabs for
indentation, and other style adjustments.
* There is no chmod() on Windows.
* Must always use the 3-parameter version of open()
* There is no dynloader.h - but it also appears unnecessary on all platforms
* Don't include shlobj.h because it causes compile errors, and from what I can
see it's not actually used. This may need to be added back for mingw
and/or cygwin in the worst case.
