Set exec_prefix in cairo-script-interpreter.pc.in
https://gitlab.freedesktop.org/cairo/cairo/-/merge_requests/324
https://gitlab.freedesktop.org/cairo/cairo/-/commit/a0dfb2c07308c8cdc2aa300a0238bc996d91aa36
--- util/cairo-script/cairo-script-interpreter.pc.in
+++ util/cairo-script/cairo-script-interpreter.pc.in
@@ -1,4 +1,5 @@
 prefix=@prefix@
+exec_prefix=@exec_prefix@
 libdir=@libdir@
 includedir=@includedir@