Add -Werror.

Also, fixed several warnings (including one bug in generateCppImpl.cpp).

Test: compiles

Bug: 32559427

Change-Id: I78375b9052c0ad447ebac638258f25bbf562712f
diff --git a/c2hal/c2hal_l.ll b/c2hal/c2hal_l.ll
index 9873de2..d5e4511 100644
--- a/c2hal/c2hal_l.ll
+++ b/c2hal/c2hal_l.ll
@@ -84,6 +84,8 @@
 %}
 
 %option yylineno
+%option nounput
+%option noinput
 %option reentrant
 %option bison-bridge
 %option bison-locations