xz: use *.gz for source instead of *.xz

On Darwin platform there is no xz-utils package provided by Apple thus
we cannot expand LZMA2 archives. Use gzip or bz2 for sources.

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
xdaq-toolfile: XDAQ OS must be macosx, not darwin

Change XDAQ OS to be 'macosx' instead of 'darwin'. Headers are installed
under 'macosx' directory and SCRAM complains if directory is missing.

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
xerces-c: fix compilation on Darwin platform

Remove Darwin 32-bit support lines and fix typos in 64-bit support. By
default Darwin is 64-bit.

Signed-off-by: David Abdurachmanov <davidlt@cern.ch>
Merge pull request #151 from davidlt/IB/CMSSW_7_0_X/devel-gcc48

[CMSSW_7_0_X][48] Updates for Darwin