We only want "linker input file unused" errors for -l<lib> options,
because things like -Wl,-O1 break configure's -fPIC detection.

diff -Nur gcc-3.4.4.orig/gcc/gcc.c gcc-3.4.4/gcc/gcc.c
--- gcc-3.4.4.orig/gcc/gcc.c	2005-05-01 10:33:14.000000000 +0000
+++ gcc-3.4.4/gcc/gcc.c	2005-08-26 01:13:17.888827271 +0000
@@ -6447,7 +6447,7 @@
 
   if (! linker_was_run && error_count == 0)
     for (i = 0; (int) i < n_infiles; i++)
-      if (explicit_link_files[i])
+      if (explicit_link_files[i] && outfiles[i][0] == '-' && outfiles[i][1] == 'l')
 	error ("%s: linker input file unused because linking not done",
 	       outfiles[i]);