Add 64-bit integer support to ASN.1 compiler

ASN.1 INTEGERs will now compile to C int64_t or uint64_t, depending
    on whether the constraint ranges include numbers that cannot be
    represented in 32-bit ints and whether they include negative
    numbers.

    Template backend support included.  check-template is now built with
    --template, so we know we're testing it.

    Tests included.

lib/asn1/symbol.h

@@ -78,7 +78,7 @@ struct value {
     } type;
     union {
 	int booleanvalue;
-	int integervalue;
+	int64_t integervalue;
 	char *stringvalue;
 	struct objid *objectidentifiervalue;
     } u;
@@ -109,8 +109,12 @@ struct tagtype {
 };
 
 struct range {
-    int min;
-    int max;
+    /*
+     * We can't represent unsigned 64-bit ranges because max might be
+     * negative...
+     */
+    int64_t min;
+    int64_t max;
 };
 
 enum ctype { CT_CONTENTS, CT_USER } ;