PHP can't be AUTORECONF with any modern autotools and the dl tests are
pretty bad for cross-compilation, so just kill the needed ac_cv value unsets
so they can flow through from the package makefile.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>

diff -Nura php-5.5.8.orig/configure php-5.5.8/configure
--- php-5.5.8.orig/configure	2014-01-28 17:41:33.943851727 -0300
+++ php-5.5.8/configure	2014-01-28 17:42:53.785493795 -0300
@@ -16985,7 +16985,6 @@
 
 
 
-  unset ac_cv_func_dlopen
   unset ac_cv_func___dlopen
   unset found
 
@@ -17013,7 +17012,6 @@
 
     *)
 
-  unset ac_cv_lib_dl_dlopen
   unset ac_cv_lib_dl___dlopen
   unset found
   { $as_echo "$as_me:${as_lineno-$LINENO}: checking for dlopen in -ldl" >&5
