[docs] Refine the description in Set-Like and Map-Like container options.

[HsiangKai]

Summary

In "Other Set-Like Container Options":

• Drops the references to C++ TR1 and SGI and hash_set.
• Drops the worry about portability (this was a problem with hash_set, but std::unordered_set has worked portably since LLVM started depending on C++11).

It is similar in "Other Map-Like Container Options" section.

[dexonsmith]

There is no container named hash_set or hash_maa in C++ STL. We should
add double quotes around the word just like previous sentence.

Not sure repeating the double-quotes makes sense; the previous sentence references to SGI and C++ TR1, both of which did have these containers. It sounds like you're using quotes because it's not a real thing, but I'm not sure that applies here.

That said, maybe it's a good idea to drop the hash_* references entirely. Not sure they're relevant anymore.

llvm/docs/ProgrammersManual.rst

2201–2205

See the proposed edit, which:

• Drops the references to C++ TR1 and SGI and hash_set.
• Drops the worry about portability (this was a problem with hash_set, but std::unordered_set has worked portably since LLVM started depending on C++11).

[HsiangKai]

llvm/docs/ProgrammersManual.rst

2201–2205

It looks good. Thanks.
I will modify it according to your suggestions.

[HsiangKai]

Update ProgrammersManual.rst according to @dexonsmith's suggestions.

[dexonsmith]

LGTM, thanks!

llvm/docs/ProgrammersManual.rst

 There is no method for returning an element of the set, you can only check for
 membership.
 
 .. _dss_otherset:
 
 Other Set-Like Container Options
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 The STL provides several other options, such as std::multiset and the various
 "hash_set" like containers (whether from C++ TR1 or from the SGI library).  We
-never use hash_set and unordered_set because they are generally very expensive
-(each insertion requires a malloc) and very non-portable.
+never use "hash_set" like containers, e.g., unordered_set, because they are
+generally very expensive (each insertion requires a malloc) and very
+non-portable.
 
 std::multiset is useful if you're not interested in elimination of duplicates,
 but has all the drawbacks of :ref:`std::set <dss_set>`.  A sorted vector
 (where you don't delete duplicate entries) or some other approach is almost
 always better.
 
 .. _ds_map:
 

 
 .. _dss_othermap:
 
 Other Map-Like Container Options
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 The STL provides several other options, such as std::multimap and the various
 "hash_map" like containers (whether from C++ TR1 or from the SGI library).  We
-never use hash_set and unordered_set because they are generally very expensive
-(each insertion requires a malloc) and very non-portable.
+never use "hash_map" like containers, e.g., unordered_map, because they are
+generally very expensive (each insertion requires a malloc) and very
+non-portable.
 
 std::multimap is useful if you want to map a key to multiple values, but has all
 the drawbacks of std::map.  A sorted vector or some other approach is almost
 always better.
 
 .. _ds_bit:
 
 Bit storage containers (BitVector, SparseBitVector, CoalescingBitVector)