site/common-linux: fix incorrect size of pid_t for apr

site/common-linux: fix incorrect size of pid_t for apr

If cross-compiling, apr's configure script assumes that pid_t is
64-bit which is wrong - it appears that 32-bit is a safe assumption
for Linux no matter what the architecture, so use that instead by
default.

This fixes Apache writing garbage to its pid file when built using apr
produced from this recipe.

(From OE-Core rev: 81eb71736a4d14abe85d810f9862d8a9421e9ef5)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>