kernel-selftest: Disable bpf tests on mips

5.4 kernel exposes a problem, where its using host includes to compile
BPF tests and it fails for mips because ptrace.h is quite different so
it can not find the needed pt_struct definitions during cross compile

% clang -fno-stack-protector -I. -I./include/uapi -I../../../include/uapi -I/mnt/b/yoe/build/tmp/work/qemumips-yoe-linux/kernel-selft
est/1.0-r0/kernel-selftest-1.0/tools/testing/selftests/bpf/../usr/include -D__TARGET_ARCH_mips -g -idirafter /mnt/b/yoe/build/tmp/wor
k/qemumips-yoe-linux/kernel-selftest/1.0-r0/recipe-sysroot-native/usr/lib/clang/10.0.0/include -Wno-compare-distinct-pointer-types -O2 -target bpf -emit-llvm \
-c progs/loop1.c
progs/loop1.c:21:9: error: no member named 'regs' in 'struct pt_regs'
m = PT_REGS_RC(ctx);
^~~~~~~~~~~~~~~
./bpf_helpers.h:466:29: note: expanded from macro 'PT_REGS_RC'

~~  ^                                                                                                        1 error generated.

Signed-off-by: Khem Raj <raj.khem@gmail.com>

meta-oe/recipes-kernel/kernel-selftest/kernel-selftest.bb

@@ -21,6 +21,10 @@ SRC_URI += "file://run-ptest \
 PACKAGECONFIG ??= "bpf vm"
 PACKAGECONFIG_remove_x86 = "bpf"
 PACKAGECONFIG_remove_arm = "bpf"
+# host ptrace.h is used to compile BPF target but mips ptrace.h is needed
+# progs/loop1.c:21:9: error: incomplete definition of type 'struct user_pt_regs'
+# m = PT_REGS_RC(ctx);
+PACKAGECONFIG_remove_qemumips = "bpf"
 
 PACKAGECONFIG[bpf] = ",,elfutils libcap libcap-ng rsync-native,"
 PACKAGECONFIG[vm] = ",,libcap,libgcc bash"
@@ -40,7 +44,7 @@ EXTRA_OEMAKE = '\
     CROSS_COMPILE=${TARGET_PREFIX} \
     ARCH=${ARCH} \
     CC="${CC}" \
-    CLANG="clang -fno-stack-protector" \
+    CLANG="clang -fno-stack-protector -arch ${ARCH} ${TOOLCHAIN_OPTIONS}" \
     AR="${AR}" \
     LD="${LD}" \
     DESTDIR="${D}" \