phyp: refactor phypListDomainsGeneric to eliminate buffer overflow

phyp: refactor phypListDomainsGeneric to eliminate buffer overflow

src/phyp/phyp_driver.c:phypListDomainsGeneric was crashing due to a buffer
overflow if any line returned from virRun wasn't <=10 characters.

Since virStrToLong_i recognizes any non-numeric as a terminator (not
just NULL), there actually is no need to copy the number into a
separate string anyway, so this patch eliminates that copy, the fixed
length buffer, and therefore the potential to overflow.

This change also provided the oppurtunity to eliminate the character
counting loop, instead using the return from virStrToLong_i to point
past the end of the number, then simply skip the \n to get to the
next.