package/lsof: fix static build

TARGET_LDFLAGS which contains -static is not passed so build fails on:

/home/buildroot/autobuild/instance-1/output-1/host/bin/xtensa-buildroot-linux-uclibc-gcc -o lsof dfile.o dmnt.o dnode.o dproc.o dsock.o dstore.o arg.o main.o misc.o node.o print.o proc.o store.o usage.o util.o -L./lib -llsof  -ltirpc
/home/buildroot/autobuild/instance-1/output-1/host/lib/gcc/xtensa-buildroot-linux-uclibc/8.3.0/../../../../xtensa-buildroot-linux-uclibc/bin/ld: /home/buildroot/autobuild/instance-1/output-1/host/lib/gcc/xtensa-buildroot-linux-uclibc/8.3.0/libgcc.a(unwind-dw2-fde-dip.o): in function `_Unwind_Find_registered_FDE':
/home/buildroot/autobuild/instance-1/output-1/build/host-gcc-final-8.3.0/build/xtensa-buildroot-linux-uclibc/libgcc/../../../libgcc/unwind-dw2-fde.c:1040: undefined reference to `dl_iterate_phdr'
collect2: error: ld returned 1 exit status

Pass TARGET_LDFLAGS thanks to LSOF_CFGL

Fixes:
 - http://autobuild.buildroot.org/results/0c228e0d3ea1ff2d728ddc906e242d40ed973222



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>