Merge branch 'bp/fsmonitor'

We learned to talk to watchman to speed up "git status" and other
operations that need to see which paths have been modified.

* bp/fsmonitor:
  fsmonitor: preserve utf8 filenames in fsmonitor-watchman log
  fsmonitor: read entirety of watchman output
  fsmonitor: MINGW support for watchman integration
  fsmonitor: add a performance test
  fsmonitor: add a sample integration script for Watchman
  fsmonitor: add test cases for fsmonitor extension
  split-index: disable the fsmonitor extension when running the split index test
  fsmonitor: add a test tool to dump the index extension
  update-index: add fsmonitor support to update-index
  ls-files: Add support in ls-files to display the fsmonitor valid bit
  fsmonitor: add documentation for the fsmonitor extension.
  fsmonitor: teach git to optionally utilize a file system monitor to speed up detecting new or changed files.
  update-index: add a new --force-write-index option
  preload-index: add override to enable testing preload-index
  bswap: add 64 bit endianness helper get_be64

environment.c

@@ -76,6 +76,7 @@ int protect_hfs = PROTECT_HFS_DEFAULT;
 #define PROTECT_NTFS_DEFAULT 0
 #endif
 int protect_ntfs = PROTECT_NTFS_DEFAULT;
+const char *core_fsmonitor;
 
 /*
  * The character that begins a commented line in user-editable file