[PATCH] perf mem: Standardize \'perf mem\' arg parsing

[Brett Holman]

This is my first time contributing here, please let me know if I
missed anything.

To compare the commands tested, use the following:

strace -f ./perf     record foo -pv bar 2>&1 | grep -a execve
strace -f ./perf mem record foo -pv bar 2>&1 | grep -a execve

Before this patch, note that '-pv' is stripped out of the command under
test for 'perf mem record', but not for 'perf record'. This patch makes
the behaviors match.