OvmfPkg: introduce QemuFwCfgSimpleParserLib

We already parse some boolean and integer values from named fw_cfg files
(usually into PCDs), and we're going to cover more. Add a dedicated
library for centralizing the parsing logic.

Cc: Ard Biesheuvel <ard.biesheuvel@arm.com>
Cc: Jordan Justen <jordan.l.justen@intel.com>
Cc: Per Sundstrom <per_sundstrom@yahoo.com>
Cc: Philippe Mathieu-Daudé <philmd@redhat.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2681
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200424075353.8489-2-lersek@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>

OvmfPkg/Library/QemuFwCfgSimpleParserLib/QemuFwCfgSimpleParserLib.inf

@@ -0,0 +1,27 @@
+## @file
+# Parse the contents of named fw_cfg files as simple (scalar) data types.
+#
+# Copyright (C) 2020, Red Hat, Inc.
+#
+# SPDX-License-Identifier: BSD-2-Clause-Patent
+##
+
+[Defines]
+  INF_VERSION                    = 1.29
+  BASE_NAME                      = QemuFwCfgSimpleParserLib
+  FILE_GUID                      = a9a1211d-061e-4b64-af30-5dd0cac9dc99
+  MODULE_TYPE                    = BASE
+  VERSION_STRING                 = 1.0
+  LIBRARY_CLASS                  = QemuFwCfgSimpleParserLib
+  CONSTRUCTOR                    = QemuFwCfgSimpleParserInit
+
+[Sources]
+  QemuFwCfgSimpleParser.c
+
+[Packages]
+  MdePkg/MdePkg.dec
+  OvmfPkg/OvmfPkg.dec
+
+[LibraryClasses]
+  BaseLib
+  QemuFwCfgLib