[libxml2] xml2-config.in: fix regressions introduced by commit 2f2bf4b2c

[Nick Wellnhofer <nwellnhof src gnome org>]

commit 29740ed12f96149e795b22a147ada80b8776c8b4
Author: Dmitry V. Levin <ldv altlinux org>
Date:   Sat Nov 2 17:51:39 2019 +0100

    xml2-config.in: fix regressions introduced by commit 2f2bf4b2c
    
    One of regressions introduced by commit
    2f2bf4b2caa1cb9a4a5039b7a44db101943382d1 aka v2.9.10-rc1~56 is that
    cflags and libs variables are used uninitialized, resulting to
    the following behaviour:
    
    $ cflags=foo libs=bar sh ./xml2-config.in --prefix
    @prefix@
    foo bar
    
    Another regression is that the test for these variables is flawed.
    
    Fixes: 2f2bf4b2c ("xml2-config.in: Output CFLAGS and LIBS on the same line")

 xml2-config.in | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/xml2-config.in b/xml2-config.in
index cb4aa613..c25558c2 100644
--- a/xml2-config.in
+++ b/xml2-config.in
@@ -4,6 +4,8 @@ prefix=@prefix@
 exec_prefix=@exec_prefix@
 includedir=@includedir@
 libdir=@libdir@
+cflags=
+libs=
 
 usage()
 {
@@ -102,7 +104,7 @@ while test $# -gt 0; do
     shift
 done
 
-if test "$cflags" -o "$libs"; then
+if test -n "$cflags$libs"; then
     echo $cflags $libs
 fi