Unobsolete string-to-multibyte

* lisp/subr.el: Un-obsolete string-to-multibyte, because it's a
useful function.  string-to-unibyte has already been un-obsoleted.
1 job for master in 73 minutes and 58 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
failed #2171
test-all

01:13:58

 
Name Stage Failure
failed
test-all Test
Makefile:318: recipe for target 'check-doit' failed
make[2]: Leaving directory '/builds/emacs/emacs/test'
Makefile:293: recipe for target 'check-expensive' failed
make[1]: Leaving directory '/builds/emacs/emacs/test'
Makefile:957: recipe for target 'check-expensive' failed
make[2]: *** [check-doit] Error 1
make[1]: *** [check-expensive] Error 2
make: *** [check-expensive] Error 2
ERROR: Job failed: exit code 1