Make sure INSTALL path is relative to the top dir when using the
script in tools/.

diff --git a/configure.ac b/configure.ac
index 9167172..5745914 100644
--- a/configure.ac
+++ b/configure.ac
@@ -83,11 +83,16 @@
 AC_PROG_RANLIB
 AC_CHECK_TOOL(STRIP,strip,strip)
 AC_CHECK_TOOL(WINDRES,windres,false)
-AC_PROG_INSTALL
 AC_PROG_LN_S
 WINE_PROG_LN
 AC_CHECK_PROG(C2MAN,c2man,c2man,\$(TOPSRCDIR)/tools/c2man.pl)
 AC_PATH_PROG(LDCONFIG, ldconfig, true, [/sbin /usr/sbin $PATH])
+AC_PROG_INSTALL
+dnl Prepend src dir to install path dir if it's a relative path
+case "$INSTALL" in
+  [\\/$]* | ?:[\\/]* ) ;;
+  *)  INSTALL="\\\$(TOPSRCDIR)/$INSTALL" ;;
+esac
 
 dnl Check for lint
 AC_CHECK_PROGS(LINT, lclint lint)