Index: libiberty/pex-unix.c
--- a/libiberty/pex-unix.c
+++ b/libiberty/pex-unix.c
@@ -1,3 +1,7 @@
+#ifdef __sun
+#define PROC_UNSUPPORTED 1
+#endif
+
 /* Utilities to execute a program in a subprocess (possibly linked by pipes
    with other subprocesses), and wait for it.  Generic Unix version
    (also used for UWIN and VMS).
