gnulib: added strcasestr

gl/unistd.in.h

@@ -21,9 +21,23 @@
 #endif
 @PRAGMA_COLUMNS@
 
+#ifdef _GL_INCLUDING_UNISTD_H
+/* Special invocation convention:
+   - On Mac OS X 10.3.9 we have a sequence of nested includes
+     <unistd.h> -> <signal.h> -> <pthread.h> -> <unistd.h>
+     In this situation, the functions are not yet declared, therefore we cannot
+     provide the C++ aliases.  */
+
+#@INCLUDE_NEXT@ @NEXT_UNISTD_H@
+
+#else
+/* Normal invocation convention.  */
+
 /* The include_next requires a split double-inclusion guard.  */
 #if @HAVE_UNISTD_H@
+# define _GL_INCLUDING_UNISTD_H
 # @INCLUDE_NEXT@ @NEXT_UNISTD_H@
+# undef _GL_INCLUDING_UNISTD_H
 #endif
 
 /* Get all possible declarations of gethostname().  */
@@ -1539,4 +1553,5 @@ _GL_CXXALIASWARN (write);
 _GL_INLINE_HEADER_END
 
 #endif /* _@GUARD_PREFIX@_UNISTD_H */
+#endif /* _GL_INCLUDING_UNISTD_H */
 #endif /* _@GUARD_PREFIX@_UNISTD_H */