We were passing -g flag twice, just uncool.

gh-1017 double-run bug fixed, and fixed same bug in stat_net. But bug with probability doesn't repeated

Make code in alter.cc less error prone and less verbose.
Miscellaneous cleanups.

Luajit comes with a custome buildsystem. Fixed passing custom
CC; it bites on FreeBSD since we are currently unable to build
with default CC (gh-786).

Issue was due to _Thread_local keyword used in the system
header which gcc4.8 fails to understand in c11 mode.
In --std=gnu99 mode it works.

Updated cmake test to claim no c11 support if ctype.h fails
to compile.

Conflicts:
	src/rmean.cc

Fixed a pair of minor bugs:
1)Fixed multidim_test, it could occasionally crash
2)Fixed rtree_misc.test.lua, snapshot test part
3)Reverted another rtree key mode -
  ind:select{0, 0, 10, 10} and
  ind:select{{0, 0, 10, 10}} - both works now

Don't create an extra port_buf object, to process a request. Eliminate
obsolete wrappers, such as process_ro().

Call box_select() directly from iproto and Lua/C bindings,
bypassing process_rw entry point. Saves a few CPU cycles
and opens the path for further refactoring.

Remove one usage of box_process which we aim to eliminate.