stdint.h on IRIX 6.5

[Olly Betts]

SGI's compiler on IRIX appears to treat "#error" as a warning.  And IRIX
uses #error in stdint.h if it's included in non-C99 mode (either C89 or C++)
and doesn't define the types if this is the case.

So trying to compile "#include <stdint.h>" works as far as configure is
concerned, but none of the types actually get defined by it when code
includes this header.  The following transcript demonstrates this:

---8<---
$ uname -sr
IRIX64 6.5
$ cc -v
MIPSpro Compilers: Version 7.4
$ cat stdinttest.c
#include <stdint.h>
int main() {return 0;}
$ cc stdinttest.c
cc-1035 cc: WARNING File = /usr/include/stdint.h, Line = 5
  #error directive:  This header file is to be used only for c99 mode
          compilations

  #error This header file is to be used only for c99 mode compilations
   ^

$ echo $?
0
$ ls -l a.out
-rwxr-xr-x    1 olly     users      20792 Oct 25 18:23 a.out
$ ./a.out
$ cat stdinttest2.c
#include <stdint.h>
int main() {return (int32_t)0;}
$ cc stdinttest2.c
cc-1035 cc: WARNING File = /usr/include/stdint.h, Line = 5
  #error directive:  This header file is to be used only for c99 mode
          compilations

  #error This header file is to be used only for c99 mode compilations
   ^

cc-1020 cc: ERROR File = stdinttest2.c, Line = 2
  The identifier "int32_t" is undefined.

  int main() {return (int32_t)0;}
                      ^

cc-1065 cc: ERROR File = stdinttest2.c, Line = 2
  A semicolon is expected at this point.

  int main() {return (int32_t)0;}
                              ^

2 errors detected in the compilation of "stdinttest2.c".
$ echo $?
2
---8<---

I've written a custom test for stdint.h which actually checks that the
types get defined, but this doesn't work because configure checks for
stdint.h itself along with the other standard ANSI headers (perhaps
because I'm also using automake and libtool).  Any suggestions for
how best to solve this problem?

I'm using autoconf 2.60, automake 1.9.6, and libtool 1.5.22.

Cheers,
    Olly