Pin child-process on older J Ruby (rspec#1261)

Gemfile

@@ -19,12 +19,19 @@ if RUBY_VERSION >= '2.4' && RUBY_ENGINE == 'ruby'
   gem 'rubocop', "~> 0.52.1"
 end
 
-if RUBY_VERSION < '2.0.0' && !!(RbConfig::CONFIG['host_os'] =~ /cygwin|mswin|mingw|bccwin|wince|emx/)
-  gem 'ffi', '< 1.9.15' # allow ffi to be installed on older rubies on windows
+# allow gems to be installed on older rubies and/or windows
+if RUBY_VERSION < '2.2.0' && !!(RbConfig::CONFIG['host_os'] =~ /cygwin|mswin|mingw|bccwin|wince|emx/)
+  gem 'ffi', '< 1.10'
+elsif RUBY_VERSION < '2.0.0' && !!(RbConfig::CONFIG['host_os'] =~ /cygwin|mswin|mingw|bccwin|wince|emx/)
+  gem 'ffi', '< 1.9.15'
 elsif RUBY_VERSION < '1.9'
   gem 'ffi', '< 1.9.19' # ffi dropped Ruby 1.8 support in 1.9.19
 else
-  gem 'ffi', '~> 1.9.25'
+  gem 'ffi', '> 1.9.24' # prevent Github security vulnerability warning
+end
+
+if RUBY_VERSION < '2.2.0' && !!(RbConfig::CONFIG['host_os'] =~ /cygwin|mswin|mingw|bccwin|wince|emx/)
+  gem "childprocess", "< 1.0.0"
 end
 
 ### deps for rdoc.info
@@ -41,8 +48,10 @@ end
 
 platforms :jruby do
   if RUBY_VERSION < '1.9.0'
-    # Pin jruby-openssl on older Rubies
+    # Pin jruby-openssl on older J Ruby
     gem "jruby-openssl", "< 0.10.0"
+    # Pin child-process on older J Ruby
+    gem "childprocess", "< 1.0.0"
   else
     gem "jruby-openssl"
   end