Fix |...| operator for inner ports/enums

The `|...|` (sizeof) operator applies to ports/enums. That has returned
a count, but it causes an internal error when used as an inner value in
a record. This fixes that internal error for ports by just making the
sizeof operator return a count.

Enums could technically be negative before this change, but that is
rejected at parse time. It seems reasonable to modify the enum value
to only be non-negative, which makes the sizeof operator easier since it
can just return a count. Changing that to return an int would
potentially break scripts that use the sizeof operator and assign it to
a count.

This could technically break code that internally sets the enum value to
a negative value, but I don't think that's a very likely use.

testing/btest/Baseline/language.sizeof/.stderr

@@ -1,2 +1,2 @@
 ### BTest baseline data generated by btest-diff. Do not edit. Use "btest -U/-u" to update. Requires BTest >= 0.63.
-expression warning in <...>/sizeof.zeek, line 73: count underflow (5 - 9)
+expression warning in <...>/sizeof.zeek, line 83: count underflow (5 - 9)

testing/btest/Baseline/language.sizeof/output

@@ -7,11 +7,13 @@ Expr: 18446744073709551612
 Signed Expr: 4
 Double -1.23: 1.230000
 Enum ENUM3: 2
+Enum in record: 2
 File 21.000000
 Function add_interface: 2
 Integer -10: 10
 Interval -5.0 secs: 5.000000
 Port 80/tcp: 65616
+Port in record: 65616
 Record [i=10, j=<uninitialized>, k=<uninitialized>]: 3
 Set: 3
 String 'Hello': 5

testing/btest/language/sizeof.zeek

@@ -20,6 +20,14 @@ type example_record: record {
 	k: int &optional;
 };
 
+type example_record_with_enum: record {
+	e: count &default = |ENUM3|;
+} &redef;
+
+type example_record_with_port: record {
+	p: count &default = |80/tcp|;
+} &redef;
+
 global a:  addr = 1.2.3.4;
 global a6: addr = [::1];
 global b:  bool = T;
@@ -36,6 +44,8 @@ global sn: subnet = 192.168.0.0/24;
 global t:  table[string] of string;
 global ti: time = current_time();
 global v:  vector of string;
+global with_enum: example_record_with_enum;
+global with_port: example_record_with_port;
 
 # Additional initialization
 #
@@ -80,6 +90,9 @@ print fmt("Double %s: %f", d, |d|);
 # Size of enum: returns numeric value of enum constant.
 print fmt("Enum %s: %d", ENUM3, |ENUM3|);
 
+# Within a record, enum sizeof should still be ok
+print fmt("Enum in record: %d", |with_enum$e|);
+
 # Size of file: returns current file size.
 # Note that this is a double so that file sizes >> 4GB
 # can be expressed.
@@ -97,6 +110,9 @@ print fmt("Interval %s: %f", iv, |iv|);
 # Size of port: returns port number as a count.
 print fmt("Port %s: %d", p, |p|);
 
+# Within a record, port sizeof should still be ok
+print fmt("Port in record: %d", |with_port$p|);
+
 # Size of record: returns number of fields (assigned + unassigned)
 print fmt("Record %s: %d", r, |r|);