Fix memory leaks as reported by DrMemory and Valgrind.

ARM and probably the rest of the arches have significant memory leaks as
they have no release interface.

Additionally, DrMemory does not have 64-bit support and thus I can't
test the 64-bit version under Windows. Under Linux valgrind supports
both 32-bit and 64-bit but there are different macros and code for Linux
and Windows.

qemu/header_gen.py

@@ -2420,7 +2420,6 @@ symbols = (
     'qemu_clock_get_us',
     'qemu_clock_ptr',
     'qemu_clocks',
-    'qemu_cond_destroy',
     'qemu_cpu_is_self',
     'qemu_cpu_kick_thread',
     'qemu_daemon',
@@ -2448,7 +2447,6 @@ symbols = (
     'qemu_log_flush',
     'qemu_loglevel_mask',
     'qemu_log_vprintf',
-    'qemu_mutex_destroy',
     'qemu_mutex_lock_ramlist',
     'qemu_mutex_trylock',
     'qemu_mutex_unlock_ramlist',