bootstrap: Ratchet up compiler strictness

Replace the specific warning flags with -Wall -Wextra and turn on
-Werror.

Covered by -Wall:

* -Wformat
* -Warray-bounds
* -Wimplicit-function-declaration

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Change-Id: Iab21e67026d2453648aa6ebe4c299e1162fc5ebf
diff --git a/astlpc.c b/astlpc.c
index 4014b89..a5a3a82 100644
--- a/astlpc.c
+++ b/astlpc.c
@@ -237,7 +237,8 @@
 		return;
 	}
 
-	if (len > astlpc->binding.pkt_size) {
+	assert(astlpc->binding.pkt_size >= 0);
+	if (len > (uint32_t)astlpc->binding.pkt_size) {
 		mctp_prwarn("invalid RX len 0x%x", len);
 		return;
 	}