Fixes #1855 and #939: improve error message when the inline mock maker cannot be used.

[raphw]

Improves the error message and does not create a hard dependency on the compiler module. It also points out that Byte Buddy can now emulate the attachment API using JNA if it's added to the class path.

[codecov-commenter]

Codecov Report

Merging #1974 into release/3.x will decrease coverage by 0.07%.
The diff coverage is 0.00%.

@@                Coverage Diff                @@
##             release/3.x    #1974      +/-   ##
=================================================
- Coverage          85.41%   85.34%   -0.08%     
  Complexity          2601     2601              
=================================================
  Files                322      322              
  Lines               7496     7505       +9     
  Branches             897      898       +1     
=================================================
+ Hits                6403     6405       +2     
- Misses               855      864       +9     
+ Partials             238      236       -2     

Impacted Files	Coverage Δ	Complexity Δ
...l/creation/bytebuddy/InlineByteBuddyMockMaker.java	57.98% <0.00%> (-3.27%)	18.00 <0.00> (ø)
...to/internal/util/concurrent/WeakConcurrentMap.java	41.48% <0.00%> (+2.12%)	11.00% <0.00%> (ø%)

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