Define _PR_POLL_AVAILABLE and _PR_USE_POLL only for glibc2.

nsprpub/pr/include/md/_linux.h

@@ -64,8 +64,10 @@
 #endif
 
 #define USE_SETJMP
+#if defined(__GLIBC__) && __GLIBC__ >= 2
 #define _PR_POLL_AVAILABLE
 #define _PR_USE_POLL
+#endif
 #define _PR_STAT_HAS_ONLY_ST_ATIME
 #if defined(__alpha)
 #define _PR_HAVE_LARGE_OFF_T