Account for the fact that std::strncmp has "C" linkage, and some

compilers don't allow to use functions with different linkage as branches
of ?: operator.


[SVN r22845]

libs/program_options

@@ -1 +1 @@
-Subproject commit e3e29890c048c8563f079a5b983af4e063ee8e7d
+Subproject commit 751e70032a5d05e33b0e7bef921e82c95ea30496