[DynInst_API:] COMMIT: fixes for GCC and Coverity warnings

[Josh Stone <jistone@xxxxxxxxxx>]

I went through gcc5 warnings and cleaned up a few things that looked like
real bugs.  The rest are mostly unused parameters and locals.  I'll probably
wait until after the next release to go for warning-clean again.

I also did a Coverity run and fixed a few of the more obvious things.

dyninst:
b7333526e894 parseAPI: correct arch comparisons in getAddressWidth
0c82d851a0a2 dyninstAPI: use parentheses to fix boolean precedence
ca85d4b9b3fd dyninstAPI: drop an unnecessary type cast
179e4bd00356 proccontrol: fix long formats for a few pthrd_printf calls
1e9e5ec5c84d dyninstAPI: fix a few c_str() pointers outliving their string
97b2ae0725aa dyninstAPI: avoid treating enums like bool
6d0d022d191e dyninstAPI: fix EmitterIA32::emitDivImm for powers of 2

testsuite:
6ee63e8e8e61 test1_6: add a div with a power-of-two immediate divisor