treewide: remove double forward declaration of read_in_full

cache.h's nature of a dumping ground of includes prevented it from
being included in some compat/ files, forcing us into a workaround
of having a double forward declaration of the read_in_full() function
(see commit 14086b0a13 ("compat/pread.c: Add a forward declaration to
fix a warning", 2007-11-17)).  Now that we have moved functions like
read_in_full() from cache.h to wrapper.h, and wrapper.h isn't littered
with unrelated and scary #defines, get rid of the extra forward
declaration and just have compat/pread.c include wrapper.h.

Signed-off-by: Elijah Newren <newren@gmail.com>
Acked-by: Calvin Wan <calvinwan@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
diff --git a/upload-pack.c b/upload-pack.c
index 0305fb2..e16dee7 100644
--- a/upload-pack.c
+++ b/upload-pack.c
@@ -32,6 +32,7 @@
 #include "commit-graph.h"
 #include "commit-reach.h"
 #include "shallow.h"
+#include "wrapper.h"
 #include "write-or-die.h"
 
 /* Remember to update object flag allocation in object.h */