QC_OS_NAME_FREEBSD uses XSI strerror_r. fixes #14

  Build using the XSI-compliant strerror_r for FreeBSD in addition to
  OSX and Solaris.  Add _POSIX_C_SOURCE check to GNU test macros.
use bourne-compliant shell in scripts
Merge pull request #14 from jfishman/master

[LLVM v3.2] qfs/src/cc/qcdio/QCUtils.cc:93: error: invalid conversion from 'int' to 'const char*