Enable JIT for AppVeyor CI

This is not supposed to bring any test performance optimization, but
allows us to test basic JIT functionality on Windows.

Author: cmb69

appveyor/test_task.bat

@@ -63,7 +63,7 @@ set OPENSSL_CONF=
 rem set SSLEAY_CONF=
 
 rem prepare for Opcache
-if "%OPCACHE%" equ "1" set OPCACHE_OPTS=-d opcache.enable=1 -d opcache.enable_cli=1 -d opcache.protect_memory=1
+if "%OPCACHE%" equ "1" set OPCACHE_OPTS=-d opcache.enable=1 -d opcache.enable_cli=1 -d opcache.protect_memory=1 -d opcache.jit_buffer_size=16M
 
 rem prepare for enchant
 mkdir c:\enchant_plugins