* dcrt0.cc (dll_crt0_1): init cygcwd before forkee branch

* environ.cc (conv_start_chars): Cache a table of "first
characters" for environment variables needing conversion.
(getwinenv): Use it.
(environ_init): Create it, also check first chars for TERM and
CYGWIN.

* path.cc: Use lookup table for case insensitive comparisons.

winsup/cygwin/dcrt0.cc

@@ -739,6 +739,8 @@ dll_crt0_1 ()
      instead of each time a file is opened. */
   set_process_privileges ();
 
+  cygcwd.init ();
+
   cygbench ("pre-forkee");
 
   if (user_data->forkee)
@@ -759,8 +761,6 @@ dll_crt0_1 ()
       longjmp (fork_info->jmp, fork_info->cygpid);
     }
 
-  cygcwd.init ();
-
   /* Initialize our process table entry. */
   pinfo_init (envp, envc);