util/fipstools/acvp/acvptool: buffer signal channel to avoid losing signal

The docs at os/signal.Notify warn about this signal delivery loss bug at
https://golang.org/pkg/os/signal/#Notify, which says:

    Package signal will not block sending to c: the caller must ensure
    that c has sufficient buffer space to keep up with the expected signal
    rate. For a channel used for notification of just one signal value,
    a buffer of size 1 is sufficient.

Discovered by one of Orijtech, Inc's internal static
analyzers that will eventually be donated to the Go project, and will
then be included when one runs:
    go test

Change-Id: I5713f7087a195ac706240d32b53d2e4855d93a1c
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/44264
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>

util/fipstools/acvp/acvptool/interactive.go

diff --git a/util/fipstools/acvp/acvptool/interactive.go b/util/fipstools/acvp/acvptool/interactive.go
index 703b41b..36d5e6c 100644
--- a/util/fipstools/acvp/acvptool/interactive.go
+++ b/util/fipstools/acvp/acvptool/interactive.go
@@ -563,7 +563,7 @@
 	defer terminal.Restore(0, oldState)
 	term := terminal.NewTerminal(os.Stdin, "> ")
 
-	resizeChan := make(chan os.Signal)
+	resizeChan := make(chan os.Signal, 1)
 	go func() {
 		for _ = range resizeChan {
 			updateTerminalSize(term)