Revert "aom_encoder: enable floating point exceptions"

This reverts commit 48c10c7d917b75d6521c54be700e1227c1647d5d.

Reason for revert: this incorrectly detects feenableexcept for
i686-w64-mingw32 (at least), causing the link to fail

BUG=aomedia:388

Change-Id: I141fec2285bd67d1312f1eb6be528cc69108cd27
6 files changed