libstdc++: Don't use reserved identifiers in simd headers
Two simd tests FAIL on Solaris, both SPARC and x86:
FAIL: experimental/simd/standard_abi_usable.cc -msse2 -O2 -Wno-psabi (test for excess errors)
FAIL: experimental/simd/standard_abi_usable_2.cc -msse2 -O2 -Wno-psabi (test for excess errors)
This happens because the simd headers use identifiers documented in the
libstdc++ manual as reserved by system headers.
Fixed as follows, tested on i386-pc-solaris2.11, sparc-sun-solaris2.11,
and x86_64-pc-linux-gnu.
2021-02-01 Rainer Orth <ro@CeBiTec.Uni-Bielefeld.DE>
libstdc++-v3:
* include/experimental/bits/simd.h: Replace reserved _X, _B by
_Xp, _Bp.
* include/experimental/bits/simd_builtin.h: Likewise.
* include/experimental/bits/simd_x86.h: Likewise.