ci: drop LGTM stuff and move remaining bits into a new location

.github/codeql-queries/PotentiallyDangerousFunction.ql

@@ -0,0 +1,59 @@
+/**
+ * vi: sw=2 ts=2 et syntax=ql:
+ *
+ * Borrowed from
+ * https://github.com/Semmle/ql/blob/master/cpp/ql/src/Security/CWE/CWE-676/PotentiallyDangerousFunction.ql
+ *
+ * @name Use of potentially dangerous function
+ * @description Certain standard library functions are dangerous to call.
+ * @id cpp/potentially-dangerous-function
+ * @kind problem
+ * @problem.severity error
+ * @precision high
+ * @tags reliability
+ *       security
+ */
+import cpp
+
+predicate potentiallyDangerousFunction(Function f, string message) {
+  (
+    f.getQualifiedName() = "fgets" and
+    message = "Call to fgets() is potentially dangerous. Use read_line() instead."
+  ) or (
+    f.getQualifiedName() = "strtok" and
+    message = "Call to strtok() is potentially dangerous. Use extract_first_word() instead."
+  ) or (
+    f.getQualifiedName() = "strsep" and
+    message = "Call to strsep() is potentially dangerous. Use extract_first_word() instead."
+  ) or (
+    f.getQualifiedName() = "dup" and
+    message = "Call to dup() is potentially dangerous. Use fcntl(fd, FD_DUPFD_CLOEXEC, 3) instead."
+  ) or (
+    f.getQualifiedName() = "htonl" and
+    message = "Call to htonl() is confusing. Use htobe32() instead."
+  ) or (
+    f.getQualifiedName() = "htons" and
+    message = "Call to htons() is confusing. Use htobe16() instead."
+  ) or (
+    f.getQualifiedName() = "ntohl" and
+    message = "Call to ntohl() is confusing. Use be32toh() instead."
+  ) or (
+    f.getQualifiedName() = "ntohs" and
+    message = "Call to ntohs() is confusing. Use be16toh() instead."
+  ) or (
+    f.getQualifiedName() = "strerror" and
+    message = "Call to strerror() is not thread-safe. Use strerror_r() or printf()'s %m format string instead."
+  ) or (
+    f.getQualifiedName() = "accept" and
+    message = "Call to accept() is not O_CLOEXEC-safe. Use accept4() instead."
+  ) or (
+    f.getQualifiedName() = "dirname" and
+    message = "Call dirname() is icky. Use path_extract_directory() instead."
+  )
+}
+
+from FunctionCall call, Function target, string message
+where
+  call.getTarget() = target and
+  potentiallyDangerousFunction(target, message)
+select call, message