Resolve conflicts in src/bin/pg_rewind/filemap.c

[RekGRpth]

1. Commit f81e97d in src/bin/pg_rewind/filemap.c removed the
   definitions of the path_cmp and get_filemap_entry functions and added
   definitions of the new insert_filehash_entry and lookup_filehash_entry
   functions. However, the earlier commit 1a770cf had already added the
   definition of get_filemap_entry.

2. Commit f81e97d in src/bin/pg_rewind/filemap.c refactored the
   process_source_file function, which had already been modified by
   earlier commits.

3. Commit f81e97d in src/bin/pg_rewind/filemap.c refactored the
   process_target_file function, which had already been modified by
   earlier commits.

4. Commit f81e97d in src/bin/pg_rewind/filemap.c refactored the code in
   the process_target_wal_block_change function, although earlier commits
   had already changed it.

5. Commit f81e97d in src/bin/pg_rewind/filemap.c removed the
   filemap_list_to_array function, and commit eb00f1d removed the
   filemap_finalize function, although earlier commit 1a770cf had already
   partially done the same.

6. Commit f81e97d in src/bin/pg_rewind/filemap.c in the
   calculate_totals function replaced the local variable filemap_t *map
   with the argument filemap_t *filemap, although earlier commit 1a770cf
   had already changed this code.

7. Commit eb00f1d added a new function, decide_file_action, to
   src/bin/pg_rewind/filemap.c. Earlier commit 1a770cf had already done
   the same, but added handling for the FILE_TYPE_FIFO case and setting
   the is_gp_tablespace field.

8. Commit eb00f1d added a new function, decide_file_actions, to
   src/bin/pg_rewind/filemap.c. Commit f81e97d refactored its contents,
   changing its return type from void to filemap_t *, and added a new
   function, hash_string_pointer. Earlier commit 1a770cf had already
   partially done the same.