toolchain: gdb: enable TUI

The GDB Text User Interface (TUI) is a terminal interface
which uses the curses library to show the source file,
the assembly output, the program registers and GDB
commands in separate text windows.

In other words it's a friendlier interface for idiots like me!

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>

toolchain/gdb/Makefile

@@ -41,7 +41,7 @@ HOST_CONFIGURE_ARGS = \
 	--target=$(REAL_GNU_TARGET_NAME) \
 	--disable-werror \
 	--without-uiout \
-	--disable-tui --disable-gdbtk --without-x \
+	--enable-tui --disable-gdbtk --without-x \
 	--without-included-gettext \
 	--enable-threads \
 	--with-expat \