Remove self comparisons in test/extern/ferguson/c_ptrs.chpl

c_ptrs.chpl had comparisons that looked like:

assert(my_ptr == my_ptr);

These now check that my_ptr != c_nil. I added a couple of overloads in
SysBasic to allow comparison between c_ptr and c_void_ptr to let us do
this.
Remove the refvar keyword

Remove refvar from the language, replacing it with the ref keyword.

Doing this requires removing the deprecated `ref(var1,var2)` task intent
syntax. Using that form will now be a syntax error rather than a
warning.

While there I cleaned up buildVarDelcs to take in a set of Flags to
apply to the variable, rather than passing them through three different
variables that would often just be set to FLAG_UNKNOWN and ignored.
Update tests to use  instead of
Merge pull request #748 from Kyle-B/kb-refvar-to-ref

Remove the refvar keyword

Remove `refvar` from the language, replacing it with the `ref` keyword.

Doing this requires removing the deprecated `ref(var1,var2)` task intent
syntax. Using that form will now be a syntax error rather than a
warning.

While there I cleaned up buildVarDelcs to take in a set of Flags to
apply to the variable, rather than passing them through three different
variables that would often just be set to FLAG_UNKNOWN and ignored.
Merge pull request #743 from Kyle-B/kb-remove-self-comparison

Remove self comparisons in test/extern/ferguson/c_ptrs.chpl

c_ptrs.chpl had comparisons that looked like:

assert(my_ptr == my_ptr);

These now check that my_ptr != c_nil. I added a couple of overloads in
SysBasic to allow comparison between c_ptr and c_void_ptr to let us do
this.