Replace specific constant tests with just type checks

As detailed in the attached issue, these constants can and do vary e.g.
between architectures on Linux.  Hardcoding and asserting that they are
equal to specific values pretty much defeats the purpose of building
these in at compile time.  Instead, simply assert that they exist and
are integers.

Fixes: #1150

core/process/constants_spec.rb

@@ -2,69 +2,91 @@
 
 describe "Process::Constants" do
   platform_is :darwin, :netbsd, :freebsd do
-    it "has the correct constant values on BSD-like systems" do
-      Process::WNOHANG.should == 1
-      Process::WUNTRACED.should == 2
-      Process::PRIO_PROCESS.should == 0
-      Process::PRIO_PGRP.should == 1
-      Process::PRIO_USER.should == 2
-      Process::RLIM_INFINITY.should == 9223372036854775807
-      Process::RLIMIT_CPU.should == 0
-      Process::RLIMIT_FSIZE.should == 1
-      Process::RLIMIT_DATA.should == 2
-      Process::RLIMIT_STACK.should == 3
-      Process::RLIMIT_CORE.should == 4
-      Process::RLIMIT_RSS.should == 5
-      Process::RLIMIT_MEMLOCK.should == 6
-      Process::RLIMIT_NPROC.should == 7
-      Process::RLIMIT_NOFILE.should == 8
+    it "are all present on BSD-like systems" do
+      %i[
+          WNOHANG
+          WUNTRACED
+          PRIO_PROCESS
+          PRIO_PGRP
+          PRIO_USER
+          RLIM_INFINITY
+          RLIMIT_CPU
+          RLIMIT_FSIZE
+          RLIMIT_DATA
+          RLIMIT_STACK
+          RLIMIT_CORE
+          RLIMIT_RSS
+          RLIMIT_MEMLOCK
+          RLIMIT_NPROC
+          RLIMIT_NOFILE
+      ].each do |const|
+        Process.const_defined?(const).should be_true
+        Process.const_get(const).should be_an_instance_of(Integer)
+      end
     end
   end
 
   platform_is :darwin do
-    it "has the correct constant values on Darwin" do
-      Process::RLIM_SAVED_MAX.should == 9223372036854775807
-      Process::RLIM_SAVED_CUR.should == 9223372036854775807
-      Process::RLIMIT_AS.should == 5
+    it "are all present on Darwin" do
+      %i[
+        RLIM_SAVED_MAX
+        RLIM_SAVED_CUR
+        RLIMIT_AS
+      ].each do |const|
+        Process.const_defined?(const).should be_true
+        Process.const_get(const).should be_an_instance_of(Integer)
+      end
     end
   end
 
   platform_is :linux do
-    it "has the correct constant values on Linux" do
-      Process::WNOHANG.should == 1
-      Process::WUNTRACED.should == 2
-      Process::PRIO_PROCESS.should == 0
-      Process::PRIO_PGRP.should == 1
-      Process::PRIO_USER.should == 2
-      Process::RLIMIT_CPU.should == 0
-      Process::RLIMIT_FSIZE.should == 1
-      Process::RLIMIT_DATA.should == 2
-      Process::RLIMIT_STACK.should == 3
-      Process::RLIMIT_CORE.should == 4
-      Process::RLIMIT_RSS.should == 5
-      Process::RLIMIT_NPROC.should == 6
-      Process::RLIMIT_NOFILE.should == 7
-      Process::RLIMIT_MEMLOCK.should == 8
-      Process::RLIMIT_AS.should == 9
-
-      # These values appear to change according to the platform.
-      values = [4294967295, 9223372036854775807, 18446744073709551615]
-      values.include?(Process::RLIM_INFINITY).should be_true
-      values.include?(Process::RLIM_SAVED_MAX).should be_true
-      values.include?(Process::RLIM_SAVED_CUR).should be_true
+    it "are all present on Linux" do
+      %i[
+        WNOHANG
+        WUNTRACED
+        PRIO_PROCESS
+        PRIO_PGRP
+        PRIO_USER
+        RLIMIT_CPU
+        RLIMIT_FSIZE
+        RLIMIT_DATA
+        RLIMIT_STACK
+        RLIMIT_CORE
+        RLIMIT_RSS
+        RLIMIT_NPROC
+        RLIMIT_NOFILE
+        RLIMIT_MEMLOCK
+        RLIMIT_AS
+        RLIM_INFINITY
+        RLIM_SAVED_MAX
+        RLIM_SAVED_CUR
+      ].each do |const|
+        Process.const_defined?(const).should be_true
+        Process.const_get(const).should be_an_instance_of(Integer)
+      end
     end
   end
 
   platform_is :netbsd, :freebsd do
-    it "has the correct constant values on NetBSD and FreeBSD" do
-      Process::RLIMIT_SBSIZE.should == 9 # FIXME: what's it equal?
-      Process::RLIMIT_AS.should == 10
+    it "are all present on NetBSD and FreeBSD" do
+      %i[
+        RLIMIT_SBSIZE
+        RLIMIT_AS
+      ].each do |const|
+        Process.const_defined?(const).should be_true
+        Process.const_get(const).should be_an_instance_of(Integer)
+      end
     end
   end
 
   platform_is :freebsd do
-    it "has the correct constant values on FreeBSD" do
-      Process::RLIMIT_NPTS.should == 11
+    it "are all present on FreeBSD" do
+      %i[
+        RLIMIT_NPTS
+      ].each do |const|
+        Process.const_defined?(const).should be_true
+        Process.const_get(const).should be_an_instance_of(Integer)
+      end
     end
   end