[openmp] [runtime] [test] Use more portable short options to sort(1)

[mgorny]

Summary

Pass -n -s instead of --numeric --stable to sort(1), as long options
are not supported by NetBSD sort implementation. -n is defined
by POSIX, so it should be fully portable. -s is used consistently
at least in GNU sort and FreeBSD sort, and I honestly doubt it would
cause issues with any other implementation supporting --stable.

openmp/trunk/runtime/test/lit.cfg

 config.substitutions.append(("%libomp-run", "%t"))
 config.substitutions.append(("%clangXX", config.test_cxx_compiler))
 config.substitutions.append(("%clang", config.test_c_compiler))
 config.substitutions.append(("%openmp_flags", config.test_openmp_flags))
 config.substitutions.append(("%flags", config.test_flags))
 
 if config.has_ompt:
     config.substitutions.append(("FileCheck", config.test_filecheck))
-    config.substitutions.append(("%sort-threads", "sort --numeric-sort --stable"))
+    config.substitutions.append(("%sort-threads", "sort -n -s"))
     if config.operating_system == 'Windows':
         # No such environment variable on Windows.
         config.substitutions.append(("%preload-tool", "true ||"))
         config.substitutions.append(("%no-as-needed-flag", "-Wl,--no-as-needed"))
     elif config.operating_system == 'Darwin':
         config.substitutions.append(("%preload-tool", "env DYLD_INSERT_LIBRARIES=%T/tool.so"))
         # No such linker flag on Darwin.
         config.substitutions.append(("%no-as-needed-flag", ""))
     else:
         config.substitutions.append(("%preload-tool", "env LD_PRELOAD=%T/tool.so"))
         config.substitutions.append(("%no-as-needed-flag", "-Wl,--no-as-needed"))