mraa.i: add idef for SWIGPYTHON on doc interface files

This fixes compilation of node.js module with doxygen

Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

src/mraa.i

@@ -5,13 +5,16 @@
 %include exception.i
 
 #ifdef DOXYGEN
-    %include common_hpp_doc.i
-    %include gpio_class_doc.i
-    %include i2c_class_doc.i
-    %include pwm_class_doc.i
-    %include aio_class_doc.i
-    %include spi_class_doc.i
-    %include uart_class_doc.i
+  //and doesn't seem to work correctly in SWIG's preprocessor
+  #ifdef SWIGPYTHON
+        %include common_hpp_doc.i
+        %include gpio_class_doc.i
+        %include i2c_class_doc.i
+        %include pwm_class_doc.i
+        %include aio_class_doc.i
+        %include spi_class_doc.i
+        %include uart_class_doc.i
+    #endif
 #endif
 
 %{