[PATCH 4 of 4 v2] auto/lib/libxslt/conf: allow to override ngx_feature_path and ngx_feature_libs

[Samuel Martin]

# HG changeset patch
# User Samuel Martin <s.martin49 at gmail.com>
# Date 1401633266 -7200
#      Sun Jun 01 16:34:26 2014 +0200
# Branch sma/cross-compilation
# Node ID 772e3e58534c255dcc32276d9aa39232f0488b5c
# Parent  c307e2addb184e7f5bcf236472e8fe21097459d3
auto/lib/libxslt/conf: allow to override ngx_feature_path and ngx_feature_libs
Because libxml2 headers are not in /usr/include by default, hardcoding the
include directory to /usr/include/libxml2 does not play well when
cross-compiling, or if libxml2 has been installed somewhere else.

This patch allows to define/override the libxslt include directory, and
the libxslt libs flags.

Being able to override the include location is especially useful when
cross-compiling to prevent gcc from complaining about unsafe include
location for cross-compilation (-Wpoision-system-directories).

So far, this warning is only triggered by libxslt.

diff -r c307e2addb18 -r 772e3e58534c auto/lib/libxslt/conf
--- a/auto/lib/libxslt/conf	Sun Jun 01 16:34:26 2014 +0200
+++ b/auto/lib/libxslt/conf	Sun Jun 01 16:34:26 2014 +0200
@@ -12,8 +12,8 @@
                       #include <libxslt/xsltInternals.h>
                       #include <libxslt/transform.h>
                       #include <libxslt/xsltutils.h>"
-    ngx_feature_path="/usr/include/libxml2"
-    ngx_feature_libs="-lxml2 -lxslt"
+    ngx_feature_path="${ngx_feature_path_libxslt:=/usr/include/libxml2}"
+    ngx_feature_libs="${ngx_feature_libs_libxslt:='-lxml2 -lxslt'}"
     ngx_feature_test="xmlParserCtxtPtr    ctxt = NULL;
                       xsltStylesheetPtr   sheet = NULL;
                       xmlDocPtr           doc;