*: add "noexcept" to many, many function prototypes

This eliminates some overhead, because the compiler doesn't need to
consider these functions throwing.

src/lib/nfs/Base.cxx

@@ -46,7 +46,7 @@ nfs_set_base(const char *server, const char *export_name)
 }
 
 const char *
-nfs_check_base(const char *server, const char *path)
+nfs_check_base(const char *server, const char *path) noexcept
 {
 	assert(server != nullptr);
 	assert(path != nullptr);