lib: Add eu_tsearch, eu_tfind, eu_tdelete and eu_tdestroy

lib: Add eu_tsearch, eu_tfind, eu_tdelete and eu_tdestroy

Add struct search_tree to hold tree root and lock.  Add new eu_t*
functions for ensuring synchronized tree access.

Replace tsearch, tfind, etc with eu_t* equivalents.

lib:
	* Makefile.am (libeu_a_SOURCES): Add eu-search.c.
	(noinst_HEADERS): Add eu-search.h and locks.h.
	* eu-config.h: Move rwlock macros to locks.h.
	* eu-search.c: New file containing tree search functions with
	  locking.
	* eu-search.h: New file.
	* locks.h: New file containing rwlock macros previously in
	  eu-config.h.
libdw:
	* cfi.h (struct Dwarf_CFI_s): Change type of search tree members
	  from void * to search_tree.
	* cie.c: Replace tree search functions with eu-search equivalents.
	* dwarf_begin_elf.c (valid_p): Initialize search trees.
	* dwarf_end.c (cu_free): Replace tree search functions
	  with eu-search equivalents.
	* dwarf_getcfi.c (dwarf_getcfi): Initialize search trees.
	* dwarf_getlocations.c: Replace search tree functions with
	  eu-search equivalents.
	  (__libdw_intern_expression): Change type of cache parameter to
	  search_tree *.
	* dwarf_getmacros.c: Replace tree search functions with
	  eu-search equivalents.
	* dwarf_getsrclines.c: Ditto.
	* fde.c: Ditto.
	* frame-cache.c (__libdw_destroy_frame_cache): Initialize search
	  trees.
	* libdwP.h (struct Dwarf): Change type of search tree members
	  from void * to search_tree.
	  (struct Dwarf_CU): Ditto.
	  (__libdw_intern_expression): Change type of cache parameter to
	  search_tree *.
	* libdw_find_split_unit.c: Replace tree search functions with
	  eu-search equivalents.
	* libdw_findcu.c: Ditto.
libdwfl:
	* cu.c: Ditto.
	* libdwflP.h (struct Dwfl_Module): Replace void *lazy_cu_root
	  with search_tree lazy_cu_tree.
libelf:
	* elf_begin.c (file_read_elf): Initialize rawchunck_tree.
	* elf_end.c (elf_end): Replace tree search function with
	  eu-search equivalent.
	* elf_getdata_rawchunck.c: Ditto.
	* libelfP.h (struct Elf): Replace void * rawchuncks member with
	search_tree rawchunk_tree.

Signed-off-by: Heather S. McIntyre <hsm2@rice.edu>
Signed-off-by: Aaron Merey <amerey@redhat.com>
Signed-off-by: Mark Wielaard <mark@klomp.org>