The following functions in meta/classes/utils.bbclass were not 
used by anyone, and they didn't work when I tried to use them:

def oe_popen_env(d):
def oe_run(d, cmd, **kwargs):
def oe_popen(d, cmd, **kwargs):
def oe_system(d, cmd, **kwargs):

There error was:
AttributeError: type object 'str' has no attribute 'getVar'

We have bitbake/lib/bb/process.py to instead, so remove them.

For meta/lib/oe/process.py, it is only used by oe_run and oe_popen which will be removed, and we have a better one: bitbake/lib/bb/process.py, so remove meta/lib/oe/process.py, too.