library: make that 'escape_str' private to our library

library: make that 'escape_str' private to our library

In that commit referenced below, a promise was made to
revisit an 'escape_str' function in efforts to make it
private to the library. The problem was it's needed by
both ps plus the library which is why it was exported.

So, in an effort to remove it from libprocps.sym, this
patch duplicates all the required code in ps/output.c.
Now, each version can be made private to their caller.

[ along the way we'll use this opportunity to remove ]
[ the 'restrict' qualifiers from function parameters ]
[ while swatting a compiler warning referenced below ]

Reference(s):
. April 2016, most escape functions made private
commit d916d5db86cbbf552401026aab15c3663412d662

proc/escape.c: In function `escape_command':
proc/escape.c:182:23: warning: initialization of `const char **' from incompatible pointer type `char **' [-Wincompatible-pointer-types]
  182 |     const char **lc = (char**)pp->cmdline;
      |                       ^

Signed-off-by: Jim Warner <james.warner@comcast.net>