When WAMR_BUILD_TARGET isn't set, choosing right target is decided
by checking `CMAKE_SIZEOF_VOID_P` variable. However, choosing `X86_32`
target is not doing specifically checking size of void pointer. It is kind
a fallback target for others.
This patch explicitly checks the size of void pointer before setting the target
to `X86_32` to fix the issue.
Some libc APIs required by wasi native lib are missing in some Android API versions, only when the version >= 24, all APIs are supported. Add the missing APIs in android platform layer, leave them empty, report error and return failed if they are called. Also update CMakeLists.txt to enable libc wasi by default.
Co-authored-by: Wenyong Huang <wenyong.huang@intel.com>
