Ruby macOS 10.13 to 10.14 API Differences

ruby/config.h

Removed #def HAVE_SYS_SYSCALL_H

Removed #def HAVE___SYSCALL

Removed #def HAVE_SYSCALL

Removed #def LGAMMA_R_M0_FIX

Added #def LGAMMA_R_PM0_FIX

ruby/ruby.h

Removed #def RB_GC_GUARD_PTR