tools/zstd: enable position independent code compilation

Currently, trying to compile LLVM-BPF will fail with:
[2225/3517] Linking CXX shared library lib/libLLVM-15.so
FAILED: lib/libLLVM-15.so
/usr/bin/ld: staging_dir/host/lib/libzstd.a(zstd_common.o): relocation R_X86_64_32 against `.rodata.str1.1' can not be used when making a shared object; recompile with -fPIC
/usr/bin/ld: failed to set dynamic section sizes: bad value
collect2: error: ld returned 1 exit status

So, to fix it enable PIC for the host ZSTD.

Fixes: #15247
Signed-off-by: Bryan Roessler <[email protected]>

tools/zstd/Makefile

@@ -17,6 +17,8 @@ include $(INCLUDE_DIR)/host-build.mk
 
 HOSTCC:= $(HOSTCC_NOCACHE)
 
+HOST_CFLAGS += $(HOST_FPIC)
+
 HOST_MAKE_FLAGS += \
 	BACKTRACE=0 \
 	HAVE_THREAD=1 \