phyp: another simplification

Rather than copying and pasting lots of code, factor it into a
single helper function.

This commit adds a warning if tighter integer parsing would fail
due to any stray bytes after the number, but should not change
any behavior other than the bug fix for phypNumDomainsGeneric
looking only at numeric lines.

* src/phyp/phyp_driver.c (phypExecInt): New function.
(phypGetVIOSPartitionID, phypNumDomainsGeneric, phypGetLparID)
(phypGetLparMem, phypGetLparCPUGeneric, phypGetRemoteSlot)
(phypGetVIOSNextSlotNumber, phypAttachDevice)
(phypGetStoragePoolSize, phypStoragePoolNumOfVolumes)
(phypNumOfStoragePools, phypInterfaceDestroy)
(phypInterfaceDefineXML, phypInterfaceLookupByName)
(phypInterfaceIsActive, phypNumOfInterfaces): Use it.
(phypNumDomainsGeneric): Correctly find numeric line.