Fix uninitialized values when parsing zeroes

[Flamefire]

00[..].e0 will not initialize the significant reference argument.

00[..]0.[0...] will not initialize exponent nor significant.

Requires

• Fix off-by-one error in parser buffer size #243

[codecov]

Codecov Report

Attention: Patch coverage is 97.22222% with 1 line in your changes missing coverage. Please review.

Project coverage is 94.85%. Comparing base (9846df1) to head (685d4b1).
Report is 6 commits behind head on develop.

Files with missing lines	Patch %	Lines
include/boost/charconv/detail/parser.hpp	90.90%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #242      +/-   ##
===========================================
+ Coverage    94.77%   94.85%   +0.08%     
===========================================
  Files           69       69              
  Lines         9050     9085      +35     
===========================================
+ Hits          8577     8618      +41     
+ Misses         473      467       -6     

Files with missing lines	Coverage Δ
test/test_parser.cpp	100.00% <100.00%> (ø)
include/boost/charconv/detail/parser.hpp	83.66% <90.90%> (+3.97%)	⬆️

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[Flamefire]

BTW: During the rebase I figured it would be easier to (re)use val and r instead of numbering them. This also eliminates the potential for a C&P error especially in valX, strlen(valX) param pair. And/Or parser could accept a string_view.

[mborland]

Other than that one comment to make windows platforms happy this looks good to me.

[Flamefire]

Other than that one comment to make windows platforms happy this looks good to me.

Fixed. A quick regex search shows a few similar issues, e.g. in fallback_routines.hpp

[mborland]

Other than that one comment to make windows platforms happy this looks good to me.

Fixed. A quick regex search shows a few similar issues, e.g. in fallback_routines.hpp

Opened #251