Use SaL symbol name when reporting breakpoint locations

Currently, "info break" can show some (perhaps) unexpected results when
setting a breakpoint on an inlined function:

(gdb) list
1	#include <stdio.h>
2
3	static inline void foo()
4	{
5	        printf("Hello world\n");
6	}
7
8	int main()
9	{
10	        foo();
11	        return 0;
12	}
13
(gdb) b foo
Breakpoint 1 at 0x400434: file foo.c, line 5.
(gdb) i b
Num     Type           Disp Enb Address            What
1       breakpoint     keep y   0x0000000000400434 in main at foo.c:5

GDB reported that we understood what "foo" was, but we then report that the
breakpoint is actually set in main. While that is literally true, we can
do a little better.

This is accomplished by copying the symbol for which the breakpoint was set
into the bp_location.  From there, print_breakpoint_location can use this
information to print out symbol information (if available) instead of calling
find_pc_sect_function.

With the patch installed,

(gdb) i b
Num     Type           Disp Enb Address            What
1       breakpoint     keep y   0x0000000000400434 in foo at foo.c:5

gdb/ChangeLog:

	* breakpoint.c (print_breakpoint_location): Use the symbol saved
	in the bp_location, falling back to find_pc_sect_function when
	needed.
	(add_location_to_breakpoint): Save sal->symbol.
	* breakpoint.h (struct bp_location) <symbol>: New field.
	* symtab.c (find_function_start_sal): Save the symbol into the SaL.
	* symtab.h (struct symtab_and_line) <symbol>: New field.

gdb/testsuite/ChangeLog:

	* gdb.opt/inline-break.exp (break_info_1): New procedure.
	Test "info break" for every inlined function breakpoint.

gdb/breakpoint.h

@@ -486,6 +486,11 @@ public:
      to find the corresponding source file name.  */
 
   struct symtab *symtab = NULL;
+
+  /* The symbol found by the location parser, if any.  This may be used to
+     ascertain when an event location was set at a different location than
+     the one originally selected by parsing, e.g., inlined symbols.  */
+  const struct symbol *symbol = NULL;
 };
 
 /* The possible return values for print_bpstat, print_it_normal,