Update to a new snapshot.

Look for ld.gold in LOCALBASE to fix builds on DragonFly. [0]

Merge a number of improvements from PR 212334 [1]:

• Use VAR option helper for _USES_PYTHON variable
• Use new GH_SUBDIR option helper, instead of post-extract-* targets
• Add libxml2 to USE_GNOME for CLANG option
• Replace blank space(s) with tab for some cases
• Add dependency on CLANG for COMPILER_RT option

Make -fopenmp work [2].

PR: 212334[1], 203223[2]
Submitted by: lightside@gmx.com[1], marino[0]
Sponsored by: DARPA, AFRL