[libgtop] configure.ac: fix cross compile error

[Robert Roth <robertroth src gnome org>]

commit 3b078fafa5e409b786d9975bbf16683aebccabb5
Author: Changqing Li <changqing li windriver com>
Date:   Fri May 21 11:14:36 2021 +0800

    configure.ac: fix cross compile error
    
    On some distros, such as fedora32, cross compile failed
    with following error since host library  is used.
    undefined reference to `stat64@GLIBC_2.33'
    
    According doc of ld, set searchdir begins with "=", but not hardcoded
    locations.
    
    Signed-off-by: Changqing Li <changqing li windriver com>

 configure.ac | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 5686c5ba..5df6bc54 100644
--- a/configure.ac
+++ b/configure.ac
@@ -284,8 +284,8 @@ AC_ARG_ENABLE(fatal-warnings,
                         [Define to enable fatal warnings]))
 
 dnl These definitions are expanded in make.
-LIBGTOP_LIBS='-L$(libdir)'
-LIBGTOP_INCS='-I$(includedir)/libgtop-2.0'
+LIBGTOP_LIBS='-L=$(libdir)'
+LIBGTOP_INCS='-I=$(includedir)/libgtop-2.0'
 
 if test x$libgtop_have_sysinfo = xyes ; then
   LIBGTOP_INCS="$LIBGTOP_INCS -DHAVE_LIBGTOP_SYSINFO"