PFFFT 3rd party: Fix pointer cast

MSVC complains about a pointer truncation caused by the VALIGNED macro in pffft.c.
The error message is: "warning C4311: 'type cast': pointer truncation from 'const float *' to 'long'"
(see https://ci.chromium.org/p/webrtc/builders/luci.webrtc.try/win_x64_msvc_dbg/3462).

This fix switches from long to uintptr_t when checking the pointer alignment in VALIGNED.

Bug: webrtc:9577
Change-Id: I086dbea5ec1f05693a77e1aebad9c83ef1055ceb
Reviewed-on: https://chromium-review.googlesource.com/c/1470154
Commit-Queue: Ale Bzk <alessiob@chromium.org>
Reviewed-by: Max Morin <maxmorin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#631709}
3 files changed