* cccp.c (do_include): Recognize c:\foo as absolute path name in DOS.

From-SVN: r10631

gcc/cccp.c

@@ -4482,6 +4482,14 @@ get_filename:
   if (*fbeg == '/'
 #ifdef DIR_SEPARATOR
       || *fbeg == DIR_SEPARATOR
+#endif
+#if defined (__MSDOS__) || defined (_WIN32)
+      || (isalpha (fbeg[0]) && fbeg[1] == ':'
+	  && (fbeg[2] == '/'
+#ifdef DIR_SEPARATOR
+	      || fbeg[2] == DIR_SEPARATOR
+#endif
+	      ))
 #endif
       ) {
     strncpy (fname, (char *) fbeg, flen);