valgrind: Note that it doesn't build with clang

packages/valgrind/build.sh

@@ -7,6 +7,9 @@ TERMUX_PKG_EXTRA_CONFIGURE_ARGS="--with-tmpdir=$TERMUX_PREFIX/tmp"
 # - Does not build on x86_64 due to lacking upstream support of that arch on android.
 #   See https://bugs.kde.org/show_bug.cgi?id=348342
 TERMUX_PKG_BLACKLISTED_ARCHES="x86_64"
+# With a clang build on aarch64:
+# "error: the clang compiler does not support '-mcpu=cortex-a8'":
+TERMUX_PKG_CLANG=no
 
 if [ "$TERMUX_ARCH" == "arm" ]; then
 	# valgrind doesn't like arm; armv7 works, though.