Fix incorrect merge of conflictant names in `dump_graphviz`

Fix incorrect merge of conflictant names in `dump_graphviz`

When using lto-dump -callgraph with two or more .o files containing distinct
functions with the same name, dump_graphviz incorrectly merged those functions
into a single node. This patch fixes this issue by calling `dump_name` instead
of `name`, therefore concat'ing the function name with the node's id.

To understeand what was the issue, let's say you have two files:

a.c: static void foo (void) { do_something (); }

b.c: static void foo (void) { do_something_else (); }

These are distinct functions and should be represented as distinct nodes in the
callgraph dump.

2019-10-22  Giuliano Belinassi  <giuliano.belinassi@usp.br>

	* cgraph.c (dump_graphviz): Change name to dump_name

From-SVN: r277299