MINOR: Move http method enum from proto_http to sample

This is useful to prevent cross includes. The header file sample.h
needs to include proto_http, stick_tables.h will need to include
sample.h and proto_http includes stick_tables.h.

I choose to move the known http method define because this enum is
mainly used in sample.h. This enum is used for the sample type method.

include/types/proto_http.h

@@ -218,20 +218,6 @@ enum {
 	PERSIST_TYPE_IGNORE,            /* ignore-persist */
 };
 
-/* Known HTTP methods */
-enum http_meth_t {
-	HTTP_METH_NONE = 0,
-	HTTP_METH_OPTIONS,
-	HTTP_METH_GET,
-	HTTP_METH_HEAD,
-	HTTP_METH_POST,
-	HTTP_METH_PUT,
-	HTTP_METH_DELETE,
-	HTTP_METH_TRACE,
-	HTTP_METH_CONNECT,
-	HTTP_METH_OTHER, /* Must be the last entry */
-} __attribute__((packed));
-
 enum ht_auth_m {
 	HTTP_AUTH_WRONG		= -1,		/* missing or unknown */
 	HTTP_AUTH_UNKNOWN	= 0,

include/types/sample.h

@@ -28,7 +28,6 @@
 
 #include <common/chunk.h>
 #include <common/mini-clist.h>
-#include <types/proto_http.h>
 
 struct arg;
 
@@ -211,6 +210,20 @@ enum {
 struct session;
 struct stream;
 
+/* Known HTTP methods */
+enum http_meth_t {
+	HTTP_METH_NONE = 0,
+	HTTP_METH_OPTIONS,
+	HTTP_METH_GET,
+	HTTP_METH_HEAD,
+	HTTP_METH_POST,
+	HTTP_METH_PUT,
+	HTTP_METH_DELETE,
+	HTTP_METH_TRACE,
+	HTTP_METH_CONNECT,
+	HTTP_METH_OTHER, /* Must be the last entry */
+} __attribute__((packed));
+
 /* a sample context might be used by any sample fetch function in order to
  * store information needed across multiple calls (eg: restart point for a
  * next occurrence). By definition it may store up to 8 pointers, or any