bc: allow {break} and {continue} (allow RBRACE to terminate them)

function                                             old     new   delta
zbc_parse_stmt_possibly_auto                        1599    1560     -39

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

testsuite/bc.tests

@@ -66,7 +66,7 @@ testing "bc if 0 else if 1" \
 	"2\n9\n" \
 	"" "if (0) 1 else if (1) 2; 9"
 
-testing "bc for(;;)" \
+testing "bc for (;;)" \
 	"bc" \
 	"2\n3\n2\n9\n" \
 	"" "i=2; for (;;) { 2; if(--i==0) break; 3; }; 9"
@@ -86,6 +86,11 @@ testing "bc for (init;cond;upd)" \
 	"1\n2\n3\n9\n" \
 	"" "for(i=1;i<4;i++)i; 9"
 
+testing "bc for (;;) {break}" \
+	"bc" \
+	"2\n9\n" \
+	"" "for (;;) {2;break}; 9"
+
 testing "bc define auto" \
 	"bc" \
 	"8\n9\n" \