libc: unsplit log message to to make it greppable in src

Also use __func__ rather than hardcoding the function name.  This code
now fits in 80 columns without splitting the log message.

Reviewed by:	zlei
Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D39619

lib/libc/stdlib/cxa_thread_atexit_impl.c

@@ -109,8 +109,9 @@ walk_cb_call(struct cxa_thread_dtor *dtor)
 	    __elf_phdr_match_addr(&phdr_info, dtor->func))
 		dtor->func(dtor->obj);
 	else
-		fprintf(stderr, "__cxa_thread_call_dtors: dtr %p from "
-		    "unloaded dso, skipping\n", (void *)(dtor->func));
+		fprintf(stderr,
+		    "__cxa_thread_call_dtors: dtr %p from unloaded dso, skipping\n",
+		    (void *)(dtor->func));
 }
 
 static void