Merge branch 'sp/stream-clean-filter'

When running a required clean filter, we do not have to mmap the
original before feeding the filter.  Instead, stream the file
contents directly to the filter and process its output.

* sp/stream-clean-filter:
  sha1_file: don't convert off_t to size_t too early to avoid potential die()
  convert: stream from fd to required clean filter to reduce used address space
  copy_fd(): do not close the input file descriptor
  mmap_limit: introduce GIT_MMAP_LIMIT to allow testing expected mmap size
  memory_limit: use git_env_ulong() to parse GIT_ALLOC_LIMIT
  config.c: add git_env_ulong() to parse environment variable
  convert: drop arguments other than 'path' from would_convert_to_git()

cache.h

@@ -1324,6 +1324,7 @@ extern int git_config_rename_section_in_file(const char *, const char *, const c
 extern const char *git_etc_gitconfig(void);
 extern int check_repository_format_version(const char *var, const char *value, void *cb);
 extern int git_env_bool(const char *, int);
+extern unsigned long git_env_ulong(const char *, unsigned long);
 extern int git_config_system(void);
 extern int config_error_nonbool(const char *);
 #if defined(__GNUC__)