Description of problem:
newlocale() neglects to set errno to an appropriate value when failing, if it has already been asked about the same incorrect locale name.

Version-Release number of selected component (if applicable):
glibc-2.14.90-24.fc16.7.x86_64

How reproducible:
100%

Steps to Reproduce:
Run this program:

#include <stdio.h>
#include <errno.h>
#include <locale.h>

int
main(int argc, char **argv)
{
  locale_t loc;

  setlocale(LC_ALL, "C");

  errno = 0;
  loc = newlocale(LC_COLLATE_MASK | LC_CTYPE_MASK,
		  "nb_no.utf8",
		  0);
  printf("result = %p errno = %d\n", loc, errno);

  errno = 0;
  loc = newlocale(LC_COLLATE_MASK | LC_CTYPE_MASK,
		  "nb_no.utf8",
		  0);
  printf("result = %p errno = %d\n", loc, errno);

  return 0;
}

  
Actual results:
result = (nil) errno = 2
result = (nil) errno = 0

Expected results:
result = (nil) errno = 2
result = (nil) errno = 2     (or at least something other than 0)

Additional info:
The problem appears to be that newlocale relies entirely on failure of an underlying open() call to set errno for such cases.  In the case where the "decided" flag is already set, no new open() calls occur, so errno doesn't get set.

I read POSIX:2008 to require errno to be set upon failure return:

Upon failure, the newlocale() function shall return ( locale_t)0 and set errno to indicate the error.