Runtime SSE detection

[qboosh]

In alg/gdalgrid.cpp there are some SSE-optimized variants of routines, but the SSE and non-SSE code is placed in the same file. Because gcc when compiling with -msse flag is allowed to emit SSE instructions anywhere in all compilation unit, it needs the same approach as AVX support, i.e. placing SSE code in separate compilation unit and compiling only this single file with -msse flag.

Example solution (against gdal 1.11.1) is attached.

[qboosh]

Isolate SSE code in separate compilation unit, compiled with -msse.

[Even Rouault]

Hum, this is probably correct, but are there actually Intel platforms those days without SSE support ?

[qboosh]

Mainstream Intel/AMD CPUs have SSE since ~10 years, but AMD Geode got SSE support later and there are many embedded units with limited extensions...

[Even Rouault]

trunk r28033 "Move gdalgrid SSE specialized implementation into a separate compilation unit (patch by qboosh, #5740)"

[Even Rouault]

Milestone renamed