MT#61856 call.h: add some macro hygiene

Expression like macroses should usually be
wrapped in parentheses.

Then they behave predictably, when for example
embedded into larger expressions,
and also so future edits do not accidentally introduce precedence bugs.

Change-Id: I4ac485c2e1ed58507f4efeec69de63a6080523c2

include/call.h

@@ -115,7 +115,7 @@ enum {
 #endif
 
 #define IS_FOREIGN_CALL(c) CALL_ISSET(c, FOREIGN)
-#define IS_OWN_CALL(c) !IS_FOREIGN_CALL(c)
+#define IS_OWN_CALL(c) (!IS_FOREIGN_CALL(c))
 
 /* flags shared by several of the structs below */
 #define SHARED_FLAG_IMPLICIT_RTCP		(1LL <<  0)