x86: set spincount 1 for x86 hybrid platform

By test, we find in hybrid platform spincount 1 is better.

Use '-march=native -Ofast -funroll-loops -flto',
results as follows:

spec2017 speed   RPL     ADL
657.xz_s         0.00%   0.50%
603.bwaves_s     10.90%  26.20%
607.cactuBSSN_s  5.50%   72.50%
619.lbm_s        2.40%   2.50%
621.wrf_s        -7.70%  2.40%
627.cam4_s       0.50%   0.70%
628.pop2_s       48.20%  153.00%
638.imagick_s    -0.10%  0.20%
644.nab_s        2.30%   1.40%
649.fotonik3d_s  8.00%   13.80%
654.roms_s       1.20%   1.10%
Geomean-int      0.00%   0.50%
Geomean-fp       6.30%   21.10%
Geomean-all      5.70%   19.10%

omp2012          RPL     ADL
350.md           -1.81%  -1.75%
351.bwaves       7.72%   12.50%
352.nab          14.63%  19.71%
357.bt331        -0.20%  1.77%
358.botsalgn     0.00%   0.00%
359.botsspar     0.00%   0.65%
360.ilbdc        0.00%   0.25%
362.fma3d        2.66%   -0.51%
363.swim         10.44%  0.00%
367.imagick      0.00%   0.12%
370.mgrid331     2.49%   25.56%
371.applu331     1.06%   4.22%
372.smithwa      0.74%   3.34%
376.kdtree       10.67%  16.03%
GEOMEAN          3.34%   5.53%

include/ChangeLog:

	PR target/109812
	* spincount.h: New file.

libgomp/ChangeLog:

	* env.c (initialize_env): Use do_adjust_default_spincount.
	* config/linux/x86/spincount.h: New file.