PARQUET-657: Do not define DISALLOW_COPY_AND_ASSIGN if already defined

This can cause conflicts with other libraries that also use this common macro (from Google's gutil library originally)

Author: Wes McKinney <wesm@apache.org>

Closes #135 from wesm/PARQUET-657 and squashes the following commits:

bc4f09b [Wes McKinney] Do not define macro if has been defined elsewhere

Author: wesm

src/parquet/util/macros.h

@@ -21,9 +21,11 @@
 // Useful macros from elsewhere
 
 // From Google gutil
+#ifndef DISALLOW_COPY_AND_ASSIGN
 #define DISALLOW_COPY_AND_ASSIGN(TypeName) \
   TypeName(const TypeName&) = delete;      \
   void operator=(const TypeName&) = delete
+#endif
 
 // ----------------------------------------------------------------------
 // From googletest