gdb: add dependency on host-flex and host-bison for Git versions

gdb versions fetched from git (such as the ARC version) will not build
with host-flex and host-bison.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Reviewed-by: Romain Naour <romain.naour@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/gdb/gdb.mk

@@ -49,8 +49,8 @@ HOST_GDB_PRE_PATCH_HOOKS += GDB_XTENSA_PRE_PATCH
 endif
 
 ifeq ($(GDB_FROM_GIT),y)
-GDB_DEPENDENCIES += host-texinfo
-HOST_GDB_DEPENDENCIES += host-texinfo
+GDB_DEPENDENCIES += host-texinfo host-flex host-bison
+HOST_GDB_DEPENDENCIES += host-texinfo host-flex host-bison
 endif
 
 # When gdb sources are fetched from the binutils-gdb repository, they