Makefile: fix parrallel (-j) installs

Currently, we would remove previously installed patches before
installing the new ones. Unfortunately, that does not play well
with heavily parallel installs.

Now, we consider it is the responsibility of the user to first
uninstall any previous version before installing a new one.

Reported-by: Markos Chandras <markos.chandras@gmail.com>
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

 # MIPS specific config options

 ## select ARCH_SUPPORTS_32

 ## select ARCH_SUPPORTS_64 if EXPERIMENTAL

 ## select ARCH_DEFAULT_32

 ## select ARCH_USE_MMU

 ## select ARCH_SUPPORTS_BOTH_ENDIAN

 ## select ARCH_DEFAULT_BE

 ## select ARCH_SUPPORTS_WITH_ARCH

 ## select ARCH_SUPPORTS_WITH_TUNE

 ## select ARCH_SUPPORTS_WITH_FLOAT

 ##

 ## help The MIPS architecture, as defined by:

 ## help     http://www.mips.com/