git-compat-util: move alloc macros to git-compat-util.h

alloc_nr, ALLOC_GROW, and ALLOC_GROW_BY are commonly used macros for
dynamic array allocation. Moving these macros to git-compat-util.h with
the other alloc macros focuses alloc.[ch] to allocation for Git objects
and additionally allows us to remove inclusions to alloc.h from files
that solely used the above macros.

Signed-off-by: Calvin Wan <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: calvin-wan-google

add-patch.c

@@ -1,7 +1,6 @@
 #include "git-compat-util.h"
 #include "add-interactive.h"
 #include "advice.h"
-#include "alloc.h"
 #include "editor.h"
 #include "environment.h"
 #include "gettext.h"

alias.c

@@ -1,6 +1,5 @@
 #include "git-compat-util.h"
 #include "alias.h"
-#include "alloc.h"
 #include "config.h"
 #include "gettext.h"
 #include "strbuf.h"