busybox: enable noclobber option in install.sh

We support a busybox-menuconfig target so that the BusyBox
configuration can be adjusted as needed.  However, depending
on what other packages are enabled, re-installing BusyBox
symlinks that duplicate "real" apps after the configuration
change can result in bad behaviors:

* At best, the BusyBox applet will be used after the
install, versus the desired "real" app.

* At worst, the built rootfs can become unbootable.

The BusyBox install.sh has some capability to avoid this issue
by means of a --noclobber option.  By default, this option is
disabled.  When enabled, the install.sh will not overwrite a
target file with a symlink or hardlink, be it an actual file
or a previously installed BusyBox link.

The install.sh's argument processing is somewhat broken, so this
patch simply changes the default value of the noclobber option
to on, rather than add --noclobber to the install.sh invocation.

Signed-off-by: Danomi Manchego <danomimanchego123@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/busybox/busybox.mk

@@ -189,6 +189,12 @@ define BUSYBOX_INSTALL_WATCHDOG_SCRIPT
 endef
 endif
 
+# Enable "noclobber" in install.sh, to prevent BusyBox from overwritting any
+# full-blown versions of apps installed by other packages with sym/hard links.
+define BUSYBOX_NOCLOBBER_INSTALL
+	$(SED) 's/^noclobber="0"$$/noclobber="1"/' $(@D)/applets/install.sh
+endef
+
 define BUSYBOX_CONFIGURE_CMDS
 	$(BUSYBOX_COPY_CONFIG)
 	$(BUSYBOX_SET_MMU)
@@ -204,6 +210,7 @@ define BUSYBOX_CONFIGURE_CMDS
 	$(BUSYBOX_SET_WATCHDOG)
 	@yes "" | $(MAKE) ARCH=$(KERNEL_ARCH) CROSS_COMPILE="$(TARGET_CROSS)" \
 		-C $(@D) oldconfig
+	$(BUSYBOX_NOCLOBBER_INSTALL)
 endef
 
 define BUSYBOX_BUILD_CMDS