Make H5FL package threadsafe

[qkoziol]

Library:

• Added mutex that obeys disable-locking-for-this-thread (DLFTT) semantics, to enable threadsafe data structures within the library that "suspend" locking when a thread has exclusive ownership of the library. (in src/H5TSdlftt_mutex.[ch])

• Initialize the threadsafe aspects of the H5FL package at library startup, when concurrency is enabled. (in src/H5.c)

• Added new H5_global_t type, with H5_GLOBAL_INIT macro, to hold and initialize threadsafe globals with complex initialization that needs to be performed dynamically at runtime. (in src/H5private.h)

• Added wrapper for atomic size_t variables. (in src/H5TSprivate.h and src/H5TSatomic.c)

• Added new H5TS_bootstrap_g DLFTT mutex in src/H5TSint.c to support new threadsafe globals. (in src/H5TSint.c)

• H5FL package changes: (in src/H5FL.c and src/H5FLprivate.h)

  • Made free list limits atomic variables when concurrency is enabled
  • Access & modify free list limit globals through wrapper macros that work in both concurrent and non-concurrent builds of the library
  • Added DLFTT mutex and info for H5_global_t to each free list
  • Use new H5_GLOBAL_INIT macro to safely initialize each free list dynamically at runtime
  • Acquire & release free list's mutex when accessing information in the list to allocate & free objects (ifdef'd out in non-concurrent builds)
  • Added DLFTT mutex to each global list-of-lists
  • Acquire & release global list-of-list's mutex when accessing information in it, mainly to add new free lists to it, as they are initialized by use within the library (ifdef'd out in non-concurrent builds)
  • Small reworkings of the garbage collection routines to separate locking from accessing free list limits better
  • Switched free list initialization macros in private header to use named fields, to make them portable between concurrency and non-concurrency builds
  • Removed unnecessary 'init' field from a few structs
  • Minor variable and struct field renamings, to help clarify their purposes

Testing:

• Added new h5_setup_local_rand() support routine to initialize h5_local_rand() with gettimeofday() or a predefined seed value.

• Expand test/tmisc.c, test_misc35(), to cover additional cases.

• Added tts_h5fl() to ttsafe test, skipped by default for non-concurrency builds.

• The tts_h5fl() testing generates multiple random test vectors of operations for each type of free list (regular, block, factory, and array) and then spawns threads that randomly chooses a set of test vectors to execute concurrently.