Append .count to anchors with the same qualified symbol name

Don't write anchors for matching ditto symbols. This helps to avoid
renumbering subsequent anchor overloads when adding a ditto item.
Matching symbols with a ditto comment don't need anchors so much
because they are near a closely-related anchor.
Add getEponymousParentTemplate function
Merge pull request #3862 from ntrel/unique-anchors

Fix Issue 9728 - Ddoc anchors non-unique across overloads
minor refactor to improve comments and error recovery
Merge pull request #4071 from WalterBright/exp-refactor

minor refactor to improve comments and error recovery
do not generate __fieldPostBlit if this(this) annotated with @disable
Comment out non-compilable AA literal
@disable __fieldPostBlit if any of postblits[] are disabled.
Fix-up type inference for function literals whose returns have been modified.
Merge pull request #4073 from IgorStepanov/disiabled-field-postblit

do not generate __fieldPostBlit if this(this) annotated with @disable
Issue 13460 - dmd can no longer be built with DEBUG=1 on Linux/x86_64
Merge pull request #4079 from IgorStepanov/checkedinn-not-compiled-in-with-debug

Issue 13460 - dmd can no longer be built with DEBUG=1 on Linux/x86_64
use an array instead of a list for global symbol list

- significantly speeds up library creation

- slist_reset is still extremely expensive
faster StringTable

- use a hash table with open addressing and linear probing
  for better cache locality
reserve enough initial capacity to avoid hash table resizes

- based on numbers from phobos compilation
Print seed for RNG in testthread2.d
Merge pull request #4081 from Safety0ff/diag13626

Diagnostic for #13626 - Print seed for RNG in testthread2.d
Merge pull request #4075 from ibuclaw/aalitnogc

Comment out non-compilable AA literal
Merge pull request #4080 from MartinNowak/arraySlist

use an array instead of a list for global symbol list
Merge pull request #4077 from ibuclaw/modifyret

Fix-up type inference for function literals whose returns have been modified