Tweak PHP_SETUP_ICONV from aclocal/acinclude.m4 to not
PHP_ADD_INCLUDE $ICONV_DIR/include since the tests use
test instead of AC_TRY_LINK to find headers which is bad,
specially when adding /usr and /usr/local to the mix.
Do basically the same with ext/iconv/config.m4 by tweaking
PHP_ICONV_H_PATH which, again, uses test and absolute paths.

Signed-off-by: Gustavo Zacarias <gustavo@zacarias.com.ar>
[Gustavo: convert to nice m4 instead of patching configure]

diff -Nura php-5.6.8.orig/acinclude.m4 php-5.6.8/acinclude.m4
--- php-5.6.8.orig/acinclude.m4	2015-05-18 20:06:48.557099001 +0200
+++ php-5.6.8/acinclude.m4	2015-05-18 20:07:33.177099001 +0200
@@ -2470,7 +2470,7 @@
   dnl
   if test "$found_iconv" = "no"; then
 
-    for i in $PHP_ICONV /usr/local /usr; do
+    for i in $PHP_ICONV; do
       if test -r $i/include/giconv.h; then
         AC_DEFINE(HAVE_GICONV_H, 1, [ ])
         ICONV_DIR=$i
diff -Nura php-5.6.7.orig/ext/iconv/config.m4 php-5.6.7/ext/iconv/config.m4
--- php-5.6.7.orig/ext/iconv/config.m4	2015-04-08 11:08:11.184847544 -0300
+++ php-5.6.7/ext/iconv/config.m4	2015-04-08 11:39:07.823608030 -0300
@@ -14,28 +14,8 @@
   ])
 
   if test "$iconv_avail" != "no"; then
-    if test -z "$ICONV_DIR"; then
-      for i in /usr/local /usr; do
-        if test -f "$i/include/iconv.h" || test -f "$i/include/giconv.h"; then
-          PHP_ICONV_PREFIX="$i"
-          break
-        fi
-      done
-      if test -z "$PHP_ICONV_PREFIX"; then
-        PHP_ICONV_PREFIX="/usr"
-      fi
-    else
-      PHP_ICONV_PREFIX="$ICONV_DIR"
-    fi
 
-    CFLAGS="-I$PHP_ICONV_PREFIX/include $CFLAGS"
-    LDFLAGS="-L$PHP_ICONV_PREFIX/$PHP_LIBDIR $LDFLAGS"
-
-    if test -r "$PHP_ICONV_PREFIX/include/giconv.h"; then
-      PHP_ICONV_H_PATH="$PHP_ICONV_PREFIX/include/giconv.h"
-    else
-      PHP_ICONV_H_PATH="$PHP_ICONV_PREFIX/include/iconv.h"
-    fi 
+    PHP_ICONV_H_PATH="iconv.h"
 
     AC_MSG_CHECKING([if iconv is glibc's])
     AC_TRY_LINK([#include <gnu/libc-version.h>],[gnu_get_libc_version();],