Redmine #6171: Improve acceptance test speed on Windows.

Run the entire test suite under one single GAINROOT umbrella, instead
of launching it for each test. This dramatically improves the testing
speed on Windows.
Demote MAX_FD Log message from ERR to WARNING, since the array is grown if needed.
Changed message wording to be symmetric with 'accepting connection'.
Merge pull request #1804 from kacfengine/faster-elevate-on-windows

Redmine #6171: Improve acceptance test speed on Windows.
Fix whoami invocation when PATH is wrong.

The path does not always contain /c/Windows/System32.
Renamed file to follow convention.
Constified username, fixed some warnings.
Fix Warning about %o expecting unsigned int.
map_test is overly slow on old platforms, speedup by avoid calling memcpy a million times.
Significantly speed up iteration test in map_test.

Basically we avoid creating a huge StringMap again, since creating takes
a long time and we've already done it before.
Print HashMap statistics in an attempt to figure out the slowness.
Do not disable unused parameters warnings in tests.

Do not disable useful warnings in generic header files, they might
actually point us to bugs in the tests. We do want to minimise warnings
during compilation, but this should be done by fixing (or suppressing
with ARG_UNUSED) each case individually.
Fix absurd numbers output from cmockery.
cmockery: show ranges in decimal instead of hex.
Indentation.
Clarified C99 status and coding guidelines.
Polish lastseen_threaded_load.
Mark unused variables as such in unit tests.

This is really frequent in unit tests, because of function stubs. I do
this now is because I recently disabled a global (in test.h) #pragma
that disables the GCC warning.
Merge pull request #1806 from jimis/misc

Misc