add volatile load/store to core.bitop
gc.config: updated comments, allow disabling command line processing, change environment var to DRT_GCOPT
Merge branch 'master' of https://github.com/D-Programming-Language/druntime into gc_config_cleanup
configure options at link time
[Refactoring] Reorder file names in MANIFEST and SRCS
[Refactoring] Gather common code in rt.util.typeinfo
fix Issue 13052 - TypeInfo.getHash should return same hash for different floating point zeros.
move drt_ variables to rt.config
add function drtConfigOption to retreive an option
show current settings in GC help message
use rt_ prefix instead of drt_, remove extern(C)
runbench: use RUN_ARGS to pass DRT arguments through command line
add C mangling depending on toolchain (needed for OSX)
Add CMSG_ALIGN and CMSG_LEN for Linux
Move the size_t cast inside the comparison so the result of CMSG_FIRSTHDR is a pointer to the first header
Note about protection of CMSG_NXTHDR
Mark at least some of CMSG_* pure, because they are
Add pure nothrow and @nogc annotations
Add inout qualifiers to CMSG_* "functions"

These are macros in the C headers, so this functionality matches there.
EXCEPT for CMSG_NXTHDR, which is a function.  It doesn't actually take
const arguments...
Add CMSG_SPACE for Linux
Make CMSG_NXTHDR a function instead of the alias, since the alias target is private
Add missing network declaration for Solaris.

These are required to compile std.socket.