Drop another unused script

The check engine abi script was never used in our build, and
with engines being on the way out, lets drop this.

gtk-engine-check-abi.sh

@@ -1,30 +0,0 @@
-#! /bin/sh
-
-# Check that a theme engine does not export any 
-# functions that may interfere with symbol resolution
-
-cat >expected-abi <<EOF
-theme_create_rc_style
-theme_exit
-theme_init
-EOF
-
-cat >optional-abi <<EOF
-__bss_start
-_edata
-_end
-_fini
-_init
-g_module_check_init
-g_module_unload
-EOF
-
-nm -D -g --defined-only $1 | cut -d ' ' -f 3 > actual-abi
-
-cat optional-abi >>expected-abi
-sort expected-abi | uniq >expected-abi2
-
-cat optional-abi >>actual-abi
-sort actual-abi | uniq >actual-abi2
-
-diff -u expected-abi2 actual-abi2 && rm expected-abi optional-abi actual-abi expected-abi2 actual-abi2