Add npm preinstall script

See nodejs#3986

Author: fhemberger

tools/osx-pkg/osx-pkg.pkgproj

@@ -1083,6 +1083,13 @@
 					<key>PATH_TYPE</key>
 					<integer>1</integer>
 				</dict>
+				<key>PREINSTALL_PATH</key>
+				<dict>
+					<key>PATH</key>
+					<string>scripts/npm_preinstall.sh</string>
+					<key>PATH_TYPE</key>
+					<integer>1</integer>
+				</dict>
 				<key>RESOURCES</key>
 				<array/>
 			</dict>
@@ -1655,7 +1662,7 @@
 			ZW50LVN0eWxlLVR5cGUiIGNvbnRlbnQ9InRleHQvY3NzIj4KPHRp
 			dGxlPjwvdGl0bGU+CjxtZXRhIG5hbWU9IkdlbmVyYXRvciIgY29u
 			dGVudD0iQ29jb2EgSFRNTCBXcml0ZXIiPgo8bWV0YSBuYW1lPSJD
-			b2NvYVZlcnNpb24iIGNvbnRlbnQ9IjEyNjUuMjEiPgo8c3R5bGUg
+			b2NvYVZlcnNpb24iIGNvbnRlbnQ9IjE0MDQuMzQiPgo8c3R5bGUg
 			dHlwZT0idGV4dC9jc3MiPgo8L3N0eWxlPgo8L2hlYWQ+Cjxib2R5
 			Pgo8L2JvZHk+CjwvaHRtbD4K
 			</data>

tools/osx-pkg/scripts/npm_preinstall.sh

@@ -0,0 +1,7 @@
+#!/bin/sh
+# TODO Can this be done inside the .pmdoc?
+# TODO Can we extract $PREFIX from the installer?
+
+set -e
+
+rm -rf /usr/local/lib/node_modules/npm