subversion: fix build failure

subversion: fix build failure

Since commit a62c0e5 apu-1-config is no longer being stipped down with
regards to being called with "--link-libtool". Example:

 $ ./staging_dir/target-mips_24kc_musl/usr/bin/apu-1-config --link-libtool
 -L/home/sk/tmp/openwrt/staging_dir/target-mips_24kc_musl/usr/lib -R/home/sk/tmp/openwrt/staging_dir/target-mips_24kc_musl/usr/lib -laprutil-1
 $

Before the mentioned commit the "-R" argument was stripped off. And when the
Makefile adds this to TARGET_LDFLAGS this then ends up in the compiler test, as
an argument for the compiler, causing build failure:

checking whether the C compiler works... no
configure: error: in `/builder/shared-workdir/build/sdk/build_dir/target-arm_mpcore+vfp_musl_eabi/subversion-1.13.0':
configure: error: C compiler cannot create executables

config.log shows what's wrong:

configure:3140: x86_64-openwrt-linux-musl-gcc -Os -pipe ... <snip> ... -R/home/sk/tmp/sdk/master-x86-64/staging_dir/target-x86_64_musl/usr/lib -laprutil-1     conftest.c  >&5
x86_64-openwrt-linux-musl-gcc: error: unrecognized command line option '-R'

This commit does away with these flags, they're not needed anyway. FPIC
is also removed, because it's detrimental to the applications [1] and
unnecessary as well.

Fixes: #11139
[1] https://wiki.gentoo.org/wiki/Project:Hardened/Position_Independent_Code_internals

Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net>