testair.cxx is a 21 lines long, obsolete test application. After removing

all lines that refer to no longer existing headers/classes/functions, then
this is what remains:  int main() { printf("boo!\n"); return 0; }

src/Airports/testair.cxx

@@ -1,21 +0,0 @@
-#include <Debug/fg_debug.h>
-#include <Include/general.h>
-#include "airports.hxx"
-
-fgGENERAL general;
-
-main() {
-    fgAIRPORTS a;
-    fgAIRPORT air;
-
-    general.root_dir = getenv("FG_ROOT");
-
-    fgInitDebug();
-
-    a.load("Airports");
-
-    air = a.search("P13");
-
-    printf("%s %lf %lf %lf\n", air.id, 
-	   air.longitude, air.latitude, air.elevation);
-}