MFH: r430520

devel/fam: unbreak with libc++ 3.9

NFSFileSystem.c++:105:12: error: assigning to 'char *' from incompatible type 'const char *'

if ((p = strstr(opt, "actimeo")))
       ^ ~~~~~~~~~~~~~~~~~~~~~~

NFSFileSystem.c++:112:12: error: assigning to 'char *' from incompatible type 'const char *'

if ((p = strstr(opt, "acregmin"))) {
       ^ ~~~~~~~~~~~~~~~~~~~~~~~

NFSFileSystem.c++:118:12: error: assigning to 'char *' from incompatible type 'const char *'

if ((p = strstr(opt, "acregmax"))) {
       ^ ~~~~~~~~~~~~~~~~~~~~~~~

PR: 212343
Regressed by: https://github.com/llvm-mirror/libcxx/commit/b4aa97130b8b