Fix autoconf path in build script

Mac builds of JetBrainsRuntime were failing with:

Autoconf is not found on the PATH, and AUTOCONF is not set.
You need autoconf to be able to generate a runnable configure script.
Error: Cannot find autoconf

Change-Id: Id7fb8bc3cfe410bea42851b56ce8d56a40e1573e
1 file changed