[tests] add test for dos line ending pre-processing

tests/spec/oracle/preprocess_dos.res.oracle

+[kernel] Parsing tests/spec/preprocess_dos.c (with preprocessing)
+/* Generated by Frama-C */
+int main(void)
+{
+  int a = 0;
+  /*@ assert a ≡ 0; */ ;
+  return a;
+}
+
+

tests/spec/preprocess_dos.c

+/* run.config*
+OPT: -cpp-command="@PTEST_DIR@/@PTEST_NAME@.sh %i %o" -cpp-frama-c-compliant -print
+*/
+
+int main() {
+    int a = 0;
+    /*@
+        assert a == 0;
+    */
+    return a;
+}

tests/spec/preprocess_dos.sh

+#!/bin/sh
+gcc -C -E -I. -o $2 $1
+dos2unix -q $2