[gimp] INSTALL: add gdb or lldb as optional runtime dependencies.

[Jehan Pagès <jehanp src gnome org>]

commit 015f2fc8007d4ec6e09196cc76b423cfcd57da0f
Author: Jehan <jehan girinstud io>
Date:   Fri Jan 26 20:18:30 2018 +0100

    INSTALL: add gdb or lldb as optional runtime dependencies.

 INSTALL.in |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/INSTALL.in b/INSTALL.in
index 58a4693..f4f0c48 100644
--- a/INSTALL.in
+++ b/INSTALL.in
@@ -180,6 +180,7 @@ header files installed.
      RawTherapee >= 5.2 for raw loading
      xdg-email for sending emails
      sendmail for sending emails if --with-sendmail enabled
+     gdb or lldb for our new bug-reporting dialog
 
 Please make sure you don't have any old GTK+-2.x, jpeg, etc. libraries
 lying around on your system, otherwise configure may fail to find the