ais.h: Fix cppcoreguidelines-macro-usage for VERSION macros

Author: schwehr

src/libais/ais.cpp

@@ -4,15 +4,13 @@
 
 #include "ais.h"
 
-extern "C" {
 int LibAisVersionMajor() {
   return LIBAIS_VERSION_MAJOR;
 }
 
 int LibAisVersionMinor() {
   return LIBAIS_VERSION_MINOR;
 }
-}  // extern "C"
 
 namespace libais {
 

src/libais/ais.h

@@ -22,14 +22,12 @@ using std::string;
 using std::unique_ptr;
 using std::vector;
 
-#define LIBAIS_VERSION_MAJOR 0
-#define LIBAIS_VERSION_MINOR 17
+constexpr int LIBAIS_VERSION_MAJOR = 0;
+constexpr int LIBAIS_VERSION_MINOR = 17;
 
-extern "C" {
 // For configuration scripts to detect libais and the version numbers.
 int LibAisVersionMajor();
 int LibAisVersionMinor();
-}
 
 namespace libais {