Convert FgetsErrorManagement to use the new dataflow library

Author: jketema

c/cert/src/rules/FIO37-C/SuccessfulFgetsOrFgetwsMayReturnAnEmptyString.ql

@@ -19,7 +19,7 @@ import cpp
 import codingstandards.c.cert
 import codingstandards.cpp.FgetsErrorManagement
 import codingstandards.cpp.Dereferenced
-import semmle.code.cpp.dataflow.DataFlow
+import semmle.code.cpp.dataflow.new.DataFlow
 
 /*
  * CFG nodes that follows a successful call to `fgets`

c/cert/test/rules/FIO40-C/ResetStringsOnFgetsOrFgetwsFailure.expected

@@ -1,6 +1,3 @@
-WARNING: module 'DataFlow' has been deprecated and may be removed in future (ResetStringsOnFgetsOrFgetwsFailure.ql:47,11-19)
-WARNING: module 'DataFlow' has been deprecated and may be removed in future (ResetStringsOnFgetsOrFgetwsFailure.ql:47,31-39)
-WARNING: module 'DataFlow' has been deprecated and may be removed in future (ResetStringsOnFgetsOrFgetwsFailure.ql:48,13-21)
 | test.c:20:10:20:12 | buf | The buffer is not reset before being referenced following a failed $@. | test.c:15:7:15:11 | call to fgets | call to fgets |
 | test.c:57:10:57:12 | buf | The buffer is not reset before being referenced following a failed $@. | test.c:52:7:52:11 | call to fgets | call to fgets |
 | test.c:66:18:66:20 | buf | The buffer is not reset before being referenced following a failed $@. | test.c:61:7:61:11 | call to fgets | call to fgets |

cpp/common/src/codingstandards/cpp/FgetsErrorManagement.qll

@@ -4,7 +4,7 @@
  */
 
 import cpp
-import semmle.code.cpp.dataflow.DataFlow
+import semmle.code.cpp.dataflow.new.DataFlow
 import semmle.code.cpp.controlflow.Guards
 
 /*