[gimp/wip/Jehan/incremental-win-installer-improvements] configure: build file-aa if AA_LIBS environment variable is set.

[Jehan <jehanp src gnome org>]

commit 53abd1e96f37463976027b20b59de66548f0016e
Author: Jehan <jehan girinstud io>
Date:   Sun May 16 16:39:09 2021 +0200

    configure: build file-aa if AA_LIBS environment variable is set.

 configure.ac | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/configure.ac b/configure.ac
index d648f47ce1..3fb9d1b03f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1663,6 +1663,9 @@ if test "x$with_aa" != xno && test -z "$AA_LIBS"; then
       FILE_AA='file-aa$(EXEEXT)'; AA_LIBS='-laa',
       [have_libaa="no (AA header file not found)"])],
     [have_libaa="no (AA library not found)"])
+elif test -n "$AA_LIBS"; then
+  have_libaa=yes
+  FILE_AA='file-aa$(EXEEXT)'
 fi
 
 AC_SUBST(FILE_AA)