x86: prevent undue use of GOT32X and alike relocations

x86: prevent undue use of GOT32X and alike relocations

Comparison of i.tm.base_opcode against particular but not sufficiently
specific values needs to be accompanied by other qualification. Exclude
VEX and alike encodings here, and also exclude all forms of prefixes
explicitly specified in the opcodes table. While using @GOT with such
insns may not be very useful, it also isn't with e.g. ADC and SBB, yet
these get explicitly listed in comments as supported.