gdb/python: smarter symbol lookup for gdb.lookup_static_symbol

gdb/python: smarter symbol lookup for gdb.lookup_static_symbol

When using gdb.lookup_static_symbol I think that GDB should find
static symbols (global symbol with static linkage) from the current
object file ahead of static symbols from other object files.

This means that if we have two source files f1.c and f2.c, and both
files contains 'static int foo;', then when we are stopped in f1.c a
call to 'gdb.lookup_static_symbol ("foo")' will find f1.c::foo, and if
we are stopped in f2.c we would find 'f2.c::foo'.

Given that gdb.lookup_static_symbol always returns a single symbol,
but there can be multiple static symbols with the same name GDB is
always making a choice about which symbols to return.  I think that it
makes sense for the choice GDB makes in this case to match what a user
would get on the command line if they asked to 'print foo'.

gdb/testsuite/ChangeLog:

	* gdb.python/py-symbol.c: Declare and call function from new
	py-symbol-2.c file.
	* gdb.python/py-symbol.exp: Compile both source files, and add new
	tests for gdb.lookup_static_symbol.
	* gdb.python/py-symbol-2.c: New file.

gdb/doc/ChangeLog:

	* python.texi (Symbols In Python): Extend documentation for
	gdb.lookup_static_symbol.

gdb/ChangeLog:

	* python/py-symbol.c (gdbpy_lookup_static_symbol): Lookup in
	static block of current object file first.  Also fix typo in
	header comment.

Change-Id: Ie55dbeb8806f35577b46015deecde27a0ca2ab64