Enable BMI1 too when using BMI2 ARCH

Adding BMI1 allows the compiler to use _blsr_u64
automatically (the advertised 0.3% speed gain).
I verified that the compiler does not use this
instruction with the -mbmi2 flag only. Also, all
processors supporting BMI2 is also supporting BMI1.

No functional change
Remove supporting pawns

Tested in no-regression mode

Passed both STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 44957 W: 7984 L: 7903 D: 29070

and LTC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 12396 W: 1916 L: 1783 D: 8697

Bench: 7907885