gdb: get rid of host-texinfo dependency

The host-texinfo dependency in gdb/host-gdb was added because gdb insisted
in building info documentation in recent versions, and we want to avoid
'makeinfo' to be present on the build system.

However, there is another solution that does not require actually building
host-texinfo: instruct the makefiles to use a dummy makeinfo command
('true').

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/gdb/gdb.mk

@@ -37,12 +37,11 @@ endif
 # also need ncurses.
 HOST_GDB_DEPENDENCIES = host-expat host-ncurses
 
-# Starting with gdb 7.10, gdb wants to re-generate its documentation.
-# We were trying to avoid that by patching the Makefiles, but it wasn't
-# working in all situations. So, we simply add a dependency on
-# host-texinfo in all case.
-GDB_DEPENDENCIES += host-texinfo
-HOST_GDB_DEPENDENCIES += host-texinfo
+# Disable building documentation
+GDB_MAKE_OPTS += MAKEINFO=true
+GDB_INSTALL_TARGET_OPTS += MAKEINFO=true
+HOST_GDB_MAKE_OPTS += MAKEINFO=true
+HOST_GDB_INSTALL_OPTS += MAKEINFO=true
 
 # Apply the Xtensa specific patches
 XTENSA_CORE_NAME = $(call qstrip, $(BR2_XTENSA_CORE_NAME))