[gimp] Allow only one exponent in numbers. From r129 of TinyScheme in SourceForge.

[Kevin Cozens <kcozens src gnome org>]

commit 0af582f309036d0940552fd7a6612d0ec33caeed
Author: Kevin Cozens <kevin ve3syb ca>
Date:   Sun Sep 27 17:20:04 2020 -0400

    Allow only one exponent in numbers. From r129 of TinyScheme in SourceForge.

 plug-ins/script-fu/tinyscheme/scheme.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/plug-ins/script-fu/tinyscheme/scheme.c b/plug-ins/script-fu/tinyscheme/scheme.c
index 82ce73cfeb..b0a5abe3fe 100644
--- a/plug-ins/script-fu/tinyscheme/scheme.c
+++ b/plug-ins/script-fu/tinyscheme/scheme.c
@@ -1211,6 +1211,7 @@ static pointer mk_atom(scheme *sc, char *q) {
                }
                else if ((c == 'e') || (c == 'E')) {
                        if(!has_fp_exp) {
+                          has_fp_exp = 1;
                           has_dec_point = 1; /* decimal point illegal
                                                 from now on */
                           p++;