Allow inlining Integer#-@ and #~

```
$ benchmark-driver -v --rbenv 'before --jit;after --jit' benchmark/mjit_integer.yml --filter '(comp|uminus)'
before --jit: ruby 3.0.0dev (2020-12-23T05:41:44Z master 0dd4896175) +JIT [x86_64-linux]
after --jit: ruby 3.0.0dev (2020-12-23T06:25:41Z master 8887d78992) +JIT [x86_64-linux]
last_commit=Allow inlining Integer#-@ and #~
Calculating -------------------------------------
                     before --jit  after --jit
        mjit_comp(1)      44.006M      70.417M i/s -     40.000M times in 0.908967s 0.568042s
      mjit_uminus(1)      44.333M      68.422M i/s -     40.000M times in 0.902255s 0.584603s

Comparison:
                     mjit_comp(1)
         after --jit:  70417331.4 i/s
        before --jit:  44005980.4 i/s - 1.60x  slower

                   mjit_uminus(1)
         after --jit:  68422468.8 i/s
        before --jit:  44333371.0 i/s - 1.54x  slower
```

1 files changed, 25 insertions, 0 deletions

diff --git a/integer.rb b/integer.rb
index b9cde8f390..d18494f42f 100644
--- a/integer.rb
+++ b/integer.rb
@@ -1,4 +1,29 @@
 class Integer
+  # call-seq:
+  #    -int  ->  integer
+  #
+  # Returns +int+, negated.
+  def -@
+    Primitive.attr! 'inline'
+    Primitive.cexpr! 'rb_int_uminus(self)'
+  end
+
+  # call-seq:
+  #   ~int  ->  integer
+  #
+  # One's complement: returns a number where each bit is flipped.
+  #
+  # Inverts the bits in an Integer. As integers are conceptually of
+  # infinite length, the result acts as if it had an infinite number of
+  # one bits to the left. In hex representations, this is displayed
+  # as two periods to the left of the digits.
+  #
+  #   sprintf("%X", ~0x1122334455)    #=> "..FEEDDCCBBAA"
+  def ~
+    Primitive.attr! 'inline'
+    Primitive.cexpr! 'rb_int_comp(self)'
+  end
+
   def abs
     Primitive.attr! 'inline'
     Primitive.cexpr! 'rb_int_abs(self)'