Implement Ada operator overloading

Implement Ada operator overloading

In the expression rewrite, I neglected to carry over support for Ada
operator overloading.  It turns out that there were no tests for this
in-tree.

This patch adds support for operator overloading, and adds the missing
test.

gdb/ChangeLog
2021-03-15  Tom Tromey  <tromey@adacore.com>

	* ada-lang.c (numeric_type_p, integer_type_p): Return true for
	fixed-point.
	* ada-exp.y (maybe_overload): New function.
	(ada_wrap_overload): New function.
	(ada_un_wrap2, ada_wrap2, ada_wrap_op): Use maybe_overload.
	(exp1, simple_exp, relation, and_exp, and_then_exp, or_exp)
	(or_else_exp, xor_exp, primary): Update.

gdb/testsuite/ChangeLog
2021-03-15  Tom Tromey  <tromey@adacore.com>

	* gdb.ada/operator_call/twovecs.ads: New file.
	* gdb.ada/operator_call/twovecs.adb: New file.
	* gdb.ada/operator_call/opcall.adb: New file.
	* gdb.ada/operator_call.exp: New file.