gdb/dwarf2: split .debug_names reading code to own file

Move everything related to reading .debug_names from read.c to
read-debug-names.c.  The only entry point exposed by
read-debug-names.{c,h} is dwarf2_read_debug_names.

Change-Id: I18b23f3c7a61b14abc3a46e4bf559bc2d078e8bc
Approved-By: Tom Tromey <tom@tromey.com>

gdb/Makefile.in

@@ -1082,6 +1082,7 @@ COMMON_SFILES = \
 	dwarf2/loc.c \
 	dwarf2/macro.c \
 	dwarf2/read.c \
+	dwarf2/read-debug-names.c \
 	dwarf2/read-gdb-index.c \
 	dwarf2/section.c \
 	dwarf2/stringify.c \
@@ -1326,6 +1327,7 @@ HFILES_NO_SRCDIR = \
 	dwarf2/index-common.h \
 	dwarf2/loc.h \
 	dwarf2/read.h \
+	dwarf2/read-debug-names.h \
 	dwarf2/read-gdb-index.h \
 	event-top.h \
 	exceptions.h \

gdb/dwarf2/read-debug-names.h

@@ -0,0 +1,30 @@
+/* Reading code for .debug_names
+
+   Copyright (C) 2023 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#ifndef DWARF2_READ_DEBUG_NAMES_H
+#define DWARF2_READ_DEBUG_NAMES_H
+
+struct dwarf2_per_objfile;
+
+/* Read .debug_names.  If everything went ok, initialize the "quick"
+   elements of all the CUs and return true.  Otherwise, return false.  */
+
+bool dwarf2_read_debug_names (dwarf2_per_objfile *per_objfile);
+
+#endif /* DWARF2_READ_DEBUG_NAMES_H */