Test cancel from indexer progress callback

This adds tests that try canceling an indexer operation from
within the progress callback.

After writing the tests, I wanted to run this under valgrind and
had a number of errors in that situation because mmap wasn't
working.  I added a CMake option to force emulation of mmap and
consolidated the Amiga-specific code into that new place (so we
don't actually need separate Amiga code now, just have to turn on
-DNO_MMAP).

Additionally, I made the indexer code propagate error codes more
reliably than it used to.

1 files changed, 2 insertions, 1 deletions

diff --git a/include/git2/pack.h b/include/git2/pack.h
index 88a2716bb..11bb559d8 100644
--- a/include/git2/pack.h
+++ b/include/git2/pack.h
@@ -52,7 +52,7 @@ typedef enum {
 	GIT_PACKBUILDER_ADDING_OBJECTS = 0,
 	GIT_PACKBUILDER_DELTAFICATION = 1,
 } git_packbuilder_stage_t;
-	
+
 /**
  * Initialize a new packbuilder
  *
@@ -143,6 +143,7 @@ GIT_EXTERN(int) git_packbuilder_write(
 GIT_EXTERN(const git_oid *) git_packbuilder_hash(git_packbuilder *pb);
 
 typedef int (*git_packbuilder_foreach_cb)(void *buf, size_t size, void *payload);
+
 /**
  * Create the new pack and pass each object to the callback
  *