bugfix: properly test null function pointer before use
Enable list iterator compile time checks

The gnu c compiler can use its preprocessor functionality to generate code
which causes compile time warnings when a wrong type for the iterator element
is used in the list helpers.

This code was removed earlier because MSVC doesn't support typeof(x).
Add video-glide64mk2 to m64p_helper_scripts
Eliminated compiler warnings about implicit pointer-to-int casts.

Using Android NDK-r8d build tools (GNU Make 3.81, gcc 4.6) generates the
following warnings in Eclipse:
warning: assignment makes integer from pointer without a cast [enabled by default]
warning: initialization makes integer from pointer without a cast [enabled by default]
merge heads
merged heads; this int-typecast change from littleguy77 is okay because it's only for the ARM target