Disable caching in HOSTRUNNER

Signed-off-by: Filipe Laíns <lains@riseup.net>

configure.ac

@@ -1609,8 +1609,8 @@ if test "$cross_compiling" = yes; then
   RUNSHARED=
 fi
 
+# HOSTRUNNER - Program to run CPython for the host platform
 AC_MSG_CHECKING([HOSTRUNNER])
-AC_ARG_VAR([HOSTRUNNER], [Program to run CPython for the host platform])
 if test -z "$HOSTRUNNER"
 then
   AS_CASE([$ac_sys_system],