Do not check for fastthread as required dependency when running in Ru…

…by 1.9.

bin/passenger-install-apache2-module

@@ -46,9 +46,11 @@ class Installer
 		Dependencies::RubyGems,
 		Dependencies::Rake,
 		Dependencies::Apache2,
-		Dependencies::Apache2_DevHeaders,
-		Dependencies::FastThread
+		Dependencies::Apache2_DevHeaders
 	]
+	if Dependencies.fastthread_required?
+		REQUIRED_DEPENDENCIES << Dependencies::FastThread
+	end
 	# Some broken servers don't have apr-config or apu-config installed.
 	# Nevertheless, it is possible to compile Apache modules if Apache
 	# was configured with --included-apr. So here we check whether

lib/phusion_passenger/dependencies.rb

@@ -90,6 +90,12 @@ def call_init_block
 # Namespace which contains the different dependencies that Passenger may require.
 # See Dependency for more information.
 module Dependencies # :nodoc: all
+	# Returns whether fastthread is a required dependency for the current
+	# Ruby interpreter.
+	def self.fastthread_required?
+		return (!defined?(RUBY_ENGINE) || RUBY_ENGINE == "ruby") && RUBY_VERSION < "1.8.7"
+	end
+
 	GCC = Dependency.new do |dep|
 		dep.name = "GNU C++ compiler"
 		dep.define_checker do |result|