fix go bindings with system-installed keystone

bindings/const_generator.py

bindings/go/README.md

bindings/go/keystone/arm64_const.go

bindings/go/keystone/arm_const.go

bindings/go/keystone/hexagon_const.go

bindings/go/keystone/keystone-binding.c

bindings/go/keystone/keystone-binding.go

bindings/go/keystone/keystone-binding.h

bindings/go/keystone/keystone.go

bindings/go/keystone/keystone_const.go

bindings/go/keystone/mips_const.go

bindings/go/keystone/ppc_const.go

bindings/go/keystone/sparc_const.go

bindings/go/keystone/systemz_const.go

bindings/go/keystone/x86_const.go