Allow reading dbclient password from an environment var

--HG--
extra : convert_revision : 9a5277c058af96e8fb7a3ade558dd1aeeafa1d3a

cli-auth.c

@@ -284,6 +284,15 @@ void cli_auth_try() {
 char* getpass_or_cancel(char* prompt)
 {
 	char* password = NULL;
+	
+#ifdef DROPBEAR_PASSWORD_ENV
+    /* Password provided in an environment var */
+    password = getenv(DROPBEAR_PASSWORD_ENV);
+    if (password)
+    {
+        return password;
+    }
+#endif
 
 	password = getpass(prompt);