trace: move trace declarations from cache.h to new trace.h

Also include direct dependencies (strbuf.h and git-compat-util.h for
__attribute__) so that trace.h can be used independently of cache.h, e.g.
in test programs.

Signed-off-by: Karsten Blees <blees@dcon.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

cache.h

@@ -7,6 +7,7 @@
 #include "advice.h"
 #include "gettext.h"
 #include "convert.h"
+#include "trace.h"
 
 #include SHA1_HEADER
 #ifndef git_SHA_CTX
@@ -1377,17 +1378,7 @@ extern void *alloc_tag_node(void);
 extern void *alloc_object_node(void);
 extern void alloc_report(void);
 
-/* trace.c */
-__attribute__((format (printf, 1, 2)))
-extern void trace_printf(const char *format, ...);
-__attribute__((format (printf, 2, 3)))
-extern void trace_argv_printf(const char **argv, const char *format, ...);
-extern void trace_repo_setup(const char *prefix);
-extern int trace_want(const char *key);
-__attribute__((format (printf, 2, 3)))
-extern void trace_printf_key(const char *key, const char *fmt, ...);
-extern void trace_strbuf(const char *key, const struct strbuf *buf);
-
+/* pkt-line.c */
 void packet_trace_identity(const char *prog);
 
 /* add */

trace.h

@@ -0,0 +1,17 @@
+#ifndef TRACE_H
+#define TRACE_H
+
+#include "git-compat-util.h"
+#include "strbuf.h"
+
+__attribute__((format (printf, 1, 2)))
+extern void trace_printf(const char *format, ...);
+__attribute__((format (printf, 2, 3)))
+extern void trace_argv_printf(const char **argv, const char *format, ...);
+extern void trace_repo_setup(const char *prefix);
+extern int trace_want(const char *key);
+__attribute__((format (printf, 2, 3)))
+extern void trace_printf_key(const char *key, const char *fmt, ...);
+extern void trace_strbuf(const char *key, const struct strbuf *buf);
+
+#endif /* TRACE_H */