package/assimp: fix static only build

package/assimp: fix static only build

Add patch to disable internal dynamic zlib library building, fixes
compile failure for static only toolchains (and assimp links
against the static one).

Fixes:

  http://autobuild.buildroot.net/results/7c2db184ee200d1719308f38f42382bb39d8d5c6

  [13%] Linking C shared library ../../lib/libzlib.so
  .../arm-buildroot-linux-uclibcgnueabi/bin/ld: .../host/arm-buildroot-linux-uclibcgnueabi/sysroot/usr/lib/libc.a(__uClibc_main.os): in function `__uClibc_fini':
  __uClibc_main.c:(.text+0x15c): undefined reference to `__fini_array_start'
  .../arm-buildroot-linux-uclibcgnueabi/bin/ld: __uClibc_main.c:(.text+0x160): undefined reference to `__fini_array_end'
  .../arm-buildroot-linux-uclibcgnueabi/bin/ld: final link failed: bad value
  collect2: error: ld returned 1 exit status

Signed-off-by: Peter Seiderer <ps.report@gmx.net>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>