Use != and == over nonzero? and zero? in hot code paths for better speed

This optimization is slightly faster.

Author: film42

lib/protobuf/field/integer_field.rb

@@ -9,7 +9,7 @@ class IntegerField < VarintField
       #
 
       def decode(value)
-        value -= 0x1_0000_0000_0000_0000 if (value & 0x8000_0000_0000_0000).nonzero?
+        value -= 0x1_0000_0000_0000_0000 if (value & 0x8000_0000_0000_0000) != 0
         value
       end
 

lib/protobuf/field/sfixed32_field.rb

@@ -10,7 +10,7 @@ class Sfixed32Field < Int32Field
 
       def decode(bytes)
         value  = bytes.unpack('V').first
-        value -= 0x1_0000_0000 if (value & 0x8000_0000).nonzero?
+        value -= 0x1_0000_0000 if (value & 0x8000_0000) != 0
         value
       end
 

lib/protobuf/field/sfixed64_field.rb

@@ -11,7 +11,7 @@ class Sfixed64Field < Int64Field
       def decode(bytes)
         values = bytes.unpack('VV') # 'Q' is machine-dependent, don't use
         value  = values[0] + (values[1] << 32)
-        value -= 0x1_0000_0000_0000_0000 if (value & 0x8000_0000_0000_0000).nonzero?
+        value -= 0x1_0000_0000_0000_0000 if (value & 0x8000_0000_0000_0000) != 0
         value
       end
 

lib/protobuf/field/signed_integer_field.rb

@@ -9,7 +9,7 @@ class SignedIntegerField < VarintField
       #
 
       def decode(value)
-        if (value & 1).zero?
+        if (value & 1) == 0
           value >> 1   # positive value
         else
           ~value >> 1  # negative value