Fix detection of CRLF line endings

[3flex]

Corrects logic to check that the character before the last '\n' is '\r', and if so, correctly report CRLF ("\r\n") line endings.

The current logic is checking the same character position that '\r' was found in also contains '\n' which always evaluates to false.

[codecov-io]

Codecov Report

Merging #2357 into master will increase coverage by 0.01%.
The diff coverage is 0%.

@@             Coverage Diff              @@
##             master    #2357      +/-   ##
============================================
+ Coverage     82.35%   82.37%   +0.01%     
  Complexity     2134     2134              
============================================
  Files           349      349              
  Lines          6058     6058              
  Branches       1110     1110              
============================================
+ Hits           4989     4990       +1     
  Misses          489      489              
+ Partials        580      579       -1

Impacted Files	Coverage Δ	Complexity Δ
...lin/io/gitlab/arturbosch/detekt/core/KtCompiler.kt	88.88% <0%> (+3.7%)	6 <0> (ø)	⬇️

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