gdb: enable simulator support for host build

Add an option to enable GDB simulator support, so
it can be used to test some no-MMU systems.

Newer GDB Blackfin Simulator need a workaround for in-tree compile.
It doesn't break for older Buildroot supported GDB Blackfin
Simulator.

Signed-off-by: Waldemar Brodkorb <wbx@openadk.org>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/gdb/Config.in.host

@@ -23,6 +23,11 @@ config BR2_PACKAGE_HOST_GDB_PYTHON
 	help
 	  This option enables the Python support in the cross gdb.
 
+config BR2_PACKAGE_HOST_GDB_SIM
+	bool "Simulator support"
+	help
+	  This option enables the simulator support in the cross gdb.
+
 choice
 	prompt "GDB debugger Version"
 	depends on !BR2_arc

package/gdb/gdb.mk

@@ -163,8 +163,7 @@ HOST_GDB_CONF_OPTS = \
 	--enable-threads \
 	--disable-werror \
 	--without-included-gettext \
-	$(GDB_DISABLE_BINUTILS_CONF_OPTS) \
-	--disable-sim
+	$(GDB_DISABLE_BINUTILS_CONF_OPTS)
 
 ifeq ($(BR2_PACKAGE_HOST_GDB_TUI),y)
 HOST_GDB_CONF_OPTS += --enable-tui
@@ -179,6 +178,20 @@ else
 HOST_GDB_CONF_OPTS += --without-python
 endif
 
+# workaround a bug if in-tree build is used for bfin sim
+define HOST_GDB_BFIN_SIM_WORKAROUND
+	$(RM) $(@D)/sim/common/tconfig.h
+endef
+
+ifeq ($(BR2_PACKAGE_HOST_GDB_SIM),y)
+HOST_GDB_CONF_OPTS += --enable-sim
+ifeq ($(BR2_bfin),y)
+HOST_GDB_PRE_CONFIGURE_HOOKS += HOST_GDB_BFIN_SIM_WORKAROUND
+endif
+else
+HOST_GDB_CONF_OPTS += --disable-sim
+endif
+
 # legacy $arch-linux-gdb symlink
 define HOST_GDB_ADD_SYMLINK
 	cd $(HOST_DIR)/usr/bin && \