TBR i#1551 Port DynamoRIO to ARM: put div routines under x86 only macro
TBR i#1551 Port DynamoRIO to ARM: put div routines under x86 only macro

There is no div instructions on most ARM arch, so we cannot easily avoid using
libgcc_s div routines on ARM.

TBR=bruening@googl.com
BUG=1551

sigma-random/dynamorio,daksunt/dynamorio,code4bones/dynamorio,code4bones/dynamorio,daksunt/dynamorio,bl4ckic3/dynamorio,daksunt/dynamorio,code4bones/dynamorio,AmesianX/dynamorio,code4bones/dynamorio,bl4ckic3/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,sigma-random/dynamorio,sigma-random/dynamorio,AmesianX/dynamorio,AmesianX/dynamorio,daksunt/dynamorio,code4bones/dynamorio,bl4ckic3/dynamorio,sigma-random/dynamorio,sigma-random/dynamorio,bl4ckic3/dynamorio,bl4ckic3/dynamorio,daksunt/dynamorio