Enumeration types are unsigned in Ada so use 'unsigned char' instead of 'char' 
for mapping Attribute_Id.

Tested x86-64/Linux, applied on the mainline.


2018-09-24  Eric Botcazou  <ebotcazou@adacore.com>

	PR ada/87396
	* fe.h (Get_Attribute_Definition_Clause): Use 'unsigned char' instead
	of 'char' as the type of the second parameter.

-- 
Eric Botcazou