ecpg: Consistently use mm_strdup()

mm_strdup() is provided to check errors from strdup(), but some places
were failing to use it.
Fix cpluspluscheck in checksum code

C++ is more picky about comparing signed and unsigned integers.
Retry short writes when flushing WAL.

We don't normally bother retrying when the number of bytes written by
write() is short of what was requested. It is generally assumed that a
write() to disk doesn't return short, unless you run out of disk space.
While writing the WAL, however, it seems prudent to try a bit harder,
because a failure leads to PANIC. The write() is also much larger than most
write()s in the backend (up to wal_buffers), so there's more room for
surprises.

Also retry on EINTR. All signals used in the backend are flagged SA_RESTART
nowadays, so it shouldn't happen, but better to be defensive.
Optimize pglz compressor for small inputs.

The pglz compressor has a significant startup cost, because it has to
initialize to zeros the history-tracking hash table. On a 64-bit system, the
hash table was 64kB in size. While clearing memory is pretty fast, for very
short inputs the relative cost of that was quite large.

This patch alleviates that in two ways. First, instead of storing pointers
in the hash table, store 16-bit indexes into the hist_entries array. That
slashes the size of the hash table to 1/2 or 1/4 of the original, depending
on the pointer width. Secondly, adjust the size of the hash table based on
input size. For very small inputs, you don't need a large hash table to
avoid collisions.

Review by Amit Kapila.
Remove undocumented -h (help) option
The -h option was not supported by many tools, and not documented, so
remove them for consistency from pg_upgrade, pg_test_fsync, and
pg_test_timing.
Update LSB URL in pg_ctl
Update Linux Standard Base Core Specification 3.1 URL mention in pg_ctl
comments.
Improve support for building PGXS modules with VPATH.

A VPATH build will be performed when the module's make file path is not
the current directory or when USE_VPATH is set.

This will assist packagers and others who prefer to build without
polluting the source directories.

There is still a bit of work to do here, notably documentation, but it's
probably a good idea to commit what we have so far and let people test
it out on their modules.

Cédric Villemain, with an addition from me.
Add timezone offset output option to to_char()
Add ability for to_char() to output the timezone's UTC offset (OF).  We
already have the ability to return the timezone abbeviation (TZ/tz).
Per request from Andrew Dunstan
pg_upgrade:  use "" rather than '', for Windows
If we ever support unix sockets on Windows, we should use "" rather than
'' for zero-length strings on the command-line, so use that.
Add a convenience routine makeFuncCall to reduce duplication.

David Fetter and Andrew Gierth, reviewed by Jeevan Chalke
pg_dump docs:  use escaped double-quotes, for Windows
On Unix, you can embed double-quotes in single-quotes, and via versa.
However, on Windows, you can only escape double-quotes in double-quotes,
so use that in the pg_dump -t/table example.
Backpatch to 9.3.
Report from Mike Toews