build: Pass NO_LIBELF/NO_LIBTRACEVENT when cross building perf

Ubuntu doesn't have a cross libelf/libtraceevent, so when cross building perf
the build fails due to the missing libraries. Pass flags to the perf build to
tell it to continue anyway.

Author: mpe

build/scripts/container-build.sh

@@ -153,6 +153,10 @@ elif [[ "$1" == "docs" ]]; then
 elif [[ "$1" == "perf" ]]; then
     cmd="make $quiet -C tools/perf O=/output"
 
+    if [[ $(uname -m) != "ppc64le" ]]; then
+        cmd+=" NO_LIBELF=1 NO_LIBTRACEEVENT=1"
+    fi
+
     if [[ -n "$PRE_CLEAN" ]]; then
         (set -x; $cmd clean)
     fi