Disable USE_SYMLINK_HEAD by default

Disable USE_SYMLINK_HEAD by default.  Recommend using it only for
compatibility with older software.

Treat USE_SYMLINK_HEAD like other optional defines - check whether it's
defined, not its value.

Signed-off-by: Pavel Roskin <proski@gnu.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Makefile

@@ -23,6 +23,9 @@ all:
 #
 # Define NO_SETENV if you don't have setenv in the C library.
 #
+# Define USE_SYMLINK_HEAD if you want .git/HEAD to be a symbolic link.
+# Don't enable it on Windows.
+#
 # Define PPC_SHA1 environment variable when running make to make use of
 # a bundled SHA1 routine optimized for PowerPC.
 #
@@ -236,7 +239,6 @@ ifeq ($(uname_O),Cygwin)
 	# NO_MMAP = YesPlease
 	NO_IPV6 = YesPlease
 	X = .exe
-	ALL_CFLAGS += -DUSE_SYMLINK_HEAD=0
 endif
 ifeq ($(uname_S),OpenBSD)
 	NO_STRCASESTR = YesPlease

refs.c

@@ -6,10 +6,6 @@
 /* We allow "recursive" symbolic refs. Only within reason, though */
 #define MAXDEPTH 5
 
-#ifndef USE_SYMLINK_HEAD
-#define USE_SYMLINK_HEAD 1
-#endif
-
 const char *resolve_ref(const char *path, unsigned char *sha1, int reading)
 {
 	int depth = MAXDEPTH, len;
@@ -80,7 +76,7 @@ int create_symref(const char *git_HEAD, const char *refs_heads_master)
 	char ref[1000];
 	int fd, len, written;
 
-#if USE_SYMLINK_HEAD
+#ifdef USE_SYMLINK_HEAD
 	if (!only_use_symrefs) {
 		unlink(git_HEAD);
 		if (!symlink(refs_heads_master, git_HEAD))