Some getrange() simplification

[alejandro-colomar]

This is part of the changes from https://github.com/shadow-maint/shadow/pull/892 (at v5).

I've decided to leave the last commits in that PR for later, since I have some ideas to do it differently. The first commits are refactors that are easier to apply separately.

Here's the range-diff vs that PR at v5:

$ git range-diff master gh/getrange gh/gr2
 1:  cb16a79a =  1:  cb16a79a lib/getrange.c: getrange(): Small refactor
 2:  06a3c8fa =  2:  06a3c8fa lib/getrange.c: getrange(): Small refactor
 3:  d25fedb2 =  3:  d25fedb2 lib/getrange.c: getrange(): Remove temporary variable
 4:  e40985b1 =  4:  e40985b1 lib/getrange.c: getrange(): Return early to remove an else
 5:  e76e4722 =  5:  e76e4722 lib/getrange.c: getrange(): Don't else after return
 6:  6fa83922 =  6:  6fa83922 lib/getrange.c: getrange(): Return early to reduce indentation
 7:  4ff016be =  7:  4ff016be lib/getrange.c: getrange(): Return early
 8:  60ed6697 =  8:  60ed6697 lib/getrange.c: getrange(): Use goto to deduplicate code
 9:  7b4fee1d =  9:  7b4fee1d lib/, src/: Rename some local variables
10:  e432eeec <  -:  -------- lib/getrange.c: getrange(): Reduce uses of non-const pointer
11:  6555aa2b <  -:  -------- lib/getrange.c: getrange(): Rename local variable
12:  2dd2c645 <  -:  -------- lib/getrange.c: getrange(): Use a2ul() instead of strtoul_noneg()
13:  baba0f11 <  -:  -------- lib/getrange.c: getrange(): Add missing cast
14:  57437f13 <  -:  -------- lib/getrange.c: getrange(): Report an ERANGE error when min>max

[alejandro-colomar]

v1b changes:

• Rebase on master

$ git range-diff master..gh/gr2 shadow/master..gr2 
 1:  cb16a79a =  1:  81ceae0d lib/getrange.c: getrange(): Small refactor
 2:  06a3c8fa =  2:  f6eb5b4c lib/getrange.c: getrange(): Small refactor
 3:  d25fedb2 =  3:  dc933d92 lib/getrange.c: getrange(): Remove temporary variable
 4:  e40985b1 =  4:  cf790923 lib/getrange.c: getrange(): Return early to remove an else
 5:  e76e4722 =  5:  2ab48e1c lib/getrange.c: getrange(): Don't else after return
 6:  6fa83922 =  6:  505dbaec lib/getrange.c: getrange(): Return early to reduce indentation
 7:  4ff016be =  7:  aa321376 lib/getrange.c: getrange(): Return early
 8:  60ed6697 =  8:  7bc7ef00 lib/getrange.c: getrange(): Use goto to deduplicate code
 9:  7b4fee1d =  9:  2daf62d9 lib/, src/: Rename some local variables

[alejandro-colomar]

Thanks! :heart: