[3.12] gh-89640: harden float word ordering (#125571 and #126387) (#126430)

Properly detect float word ordering on Linux (gh-125571)

autoconf-archive patch by Dan Amelang.

(cherry picked from commit 26d627779f79d8d5650fe7be348432eccc28f8f9)

Hardcode WASM float word ordering to little endian (gh-126387)

(cherry picked from commit 532fc08102d62c04d55f5b8aac00bd9e7e12ff4b)