refactor(expect): also capture EOF when using expectation helpers

In the OpenCI there's no possibility of a timeout when running Expect
scripts, but there can be an EOF. This change modifies the
`expect_string` and `expect_re` functions to report that a match was not
found when an early EOF is detected.

Signed-off-by: Chris Kay <chris.kay@arm.com>
Change-Id: I12fbfc86456d20e058f46b388f389d057b9d734c
diff --git a/expect/utils.inc b/expect/utils.inc
index 3d5a7f5..fc63529 100644
--- a/expect/utils.inc
+++ b/expect/utils.inc
@@ -53,6 +53,12 @@
 		$the_string {
 			puts "<<$the_message>>"
 		}
+
+		eof {
+			puts "<<not found: \"$the_string\">>"
+			exit -1
+		}
+
 		timeout {
 			puts "<<Not found: $the_string>>"
 			exit_timeout
@@ -72,6 +78,12 @@
 		-re $the_re {
 			puts "<<$the_message>>"
 		}
+
+		eof {
+			puts "<<not found: \"$the_re\">>"
+			exit -1
+		}
+
 		timeout {
 			puts "<<Not found: $the_re>>"
 			exit_timeout