Always check against optional flag

acinclude.diff

diff --git a/acinclude.m4 b/acinclude.m4
index a4d4d50..3f69968 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -1031,24 +1031,26 @@ dnl The extension on which it depends must also have been configured.
 dnl See ADD_EXTENSION_DEP in win32 build 
 dnl
 AC_DEFUN([PHP_ADD_EXTENSION_DEP], [
-  am_i_shared=$[PHP_]translit($1,a-z_-,A-Z__)[_SHARED]
-  is_it_shared=$[PHP_]translit($2,a-z_-,A-Z__)[_SHARED]
-  is_it_enabled=$[PHP_]translit($2,a-z_-,A-Z__)
-  if test "$am_i_shared" = "no" && test "$is_it_shared" = "yes" ; then
-    AC_MSG_ERROR([
+  if test "x$3" != "xtrue"; then
+    am_i_shared=$[PHP_]translit($1,a-z_-,A-Z__)[_SHARED]
+    is_it_shared=$[PHP_]translit($2,a-z_-,A-Z__)[_SHARED]
+    is_it_enabled=$[PHP_]translit($2,a-z_-,A-Z__)
+    if test "$am_i_shared" = "no" && test "$is_it_shared" = "yes" ; then
+      AC_MSG_ERROR([
 You've configured extension $1 to build statically, but it
 depends on extension $2, which you've configured to build shared.
 You either need to build $1 shared or build $2 statically for the
 build to be successful.
 ])
-  fi
-  if test "x$is_it_enabled" = "xno" && test "x$3" != "xtrue"; then
-    AC_MSG_ERROR([
+    fi
+    if test "x$is_it_enabled" = "xno"; then
+      AC_MSG_ERROR([
 You've configured extension $1, which depends on extension $2,
 but you've either not enabled $2, or have disabled it.
 ])
+    fi
+    dnl Some systems require that we link $2 to $1 when building
   fi
-  dnl Some systems require that we link $2 to $1 when building
 ])
 
 dnl -------------------------------------------------------------------------