Fix Windows interrupt count bug.

[dbwiddis]

Fixes #599. Fixes #602.

[codecov-io]

Codecov Report

Merging #604 into master will increase coverage by 0.01%.
The diff coverage is 50%.

@@             Coverage Diff              @@
##             master     #604      +/-   ##
============================================
+ Coverage     84.08%   84.09%   +0.01%     
  Complexity      197      197              
============================================
  Files            28       28              
  Lines          1420     1421       +1     
  Branches        209      209              
============================================
+ Hits           1194     1195       +1     
  Misses          105      105              
  Partials        121      121

Impacted Files	Coverage Δ	Complexity Δ
.../src/main/java/oshi/hardware/CentralProcessor.java	100% <ø> (ø)	0 <0> (ø)	⬇️
...core/src/main/java/oshi/util/ExecutingCommand.java	74.07% <33.33%> (ø)	0 <0> (ø)	⬇️
oshi-core/src/main/java/oshi/util/ParseUtil.java	95.85% <66.66%> (+0.02%)	0 <0> (ø)	⬇️

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