harfbuzz: check in harfbuzz-ng, add gyp define to use it

third_party/harfbuzz-ng/src/check-internal-symbols.sh

Index: third_party/harfbuzz-ng/src/check-internal-symbols.sh
diff --git a/third_party/harfbuzz-ng/src/check-internal-symbols.sh b/third_party/harfbuzz-ng/src/check-internal-symbols.sh
new file mode 100755
index 0000000000000000000000000000000000000000..124a7b04d3b0890b848ac3f106c48a907fd771c3
--- /dev/null
+++ b/third_party/harfbuzz-ng/src/check-internal-symbols.sh
@@ -0,0 +1,28 @@
+#!/bin/sh
+
+LC_ALL=C
+export LC_ALL
+
+if which nm 2>/dev/null >/dev/null; then
+	:
+else
+	echo "check-internal-symbols.sh: 'nm' not found; skipping test"
+	exit 0
+fi
+
+test -z "$srcdir" && srcdir=.
+test -z "$MAKE" && MAKE=make
+stat=0
+
+so=.libs/libharfbuzz.so
+if test -f "$so"; then
+	echo "Checking that we are exposing internal symbols"
+	if nm $so | grep ' T ' | grep -v ' T _fini\>\| T _init\>\| T hb_'; then
+		echo "Ouch, internal symbols exposed"
+		stat=1
+	fi
+else
+	echo "check-internal-symbols.sh: libharfbuzz.so not found; skipping test"
+fi
+
+exit $stat