Try: safe scaling ROTG

[weslleyspereira]

Replaces the original xROTG routines with Edward Anderson's safe scaling algorithms (https://doi.org/10.1145/3061665). I added some minor modifications to them.

Since the codes were written in the Fortran90 standard, I removed

# Tell CMake that our Fortran sources are written in Fixed Format.
set(CMAKE_Fortran_FORMAT FIXED)

from the CMakeLists.txt. The compiler now determines the Fortran layout by the file extension.

[codecov]

Codecov Report

Merging #527 (5a929d8) into master (77a0ceb) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #527   +/-   ##
=======================================
  Coverage   83.36%   83.36%           
=======================================
  Files        1820     1820           
  Lines      185545   185545           
=======================================
  Hits       154673   154673           
  Misses      30872    30872           

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