Check happy path first when comparing gem version

[Edouard-chin]

Note

Reviewing with ?w=1 is recommended.

What was the end-user or developer problem that led to this PR?

Checking Gem::Version can be micro optimized by checking happy path first.

What is your fix for the problem, implemented in this PR?

During resolution, Gem::Version are compared against each other. Since comparing versions is a very hot path we can micro optimize it to check the happy path first.

The speed gain on the overall resolution isn't significant but the ips gain is quite substantial. The diff chunk is small so I figure it's worth it anyway.

a = Gem::Version.new("5.3.1")
b = Gem::Version.new("5.3.1")

Benchmark.ips do |x|
  x.report("equal regular:") { a <=> c }
  x.report("equal optimized:") { a <=> c }
  x.hold!("equal_temp_results")
  x.compare!(order: :baseline)
end

Warming up --------------------------------------
      equal optimized:     1.268M i/100ms
Calculating -------------------------------------
      equal optimized:     12.738M (± 1.5%) i/s   (78.50 ns/i) -     64.680M in   5.078754s

Comparison: equal regular::  9866605.0 i/s equal optimized:: 12738310.3 i/s - 1.29x  faster 

Make sure the following tasks are checked

• Describe the problem / feature
• Write tests for features and bug fixes
• Write code to solve the problem
• Make sure you follow the current code style and write meaningful commit messages without tags

cc/ @skipkayhil