fixes #5816: boost shared build failed with MingW due to .dll.a files

[Chnossos]

boost/all

Fixes shared build with MinGW under Windows.

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[ghost]

I detected other pull requests that are modifying boost/all recipe:

• [boost] Apply patch to fix https://github.com/boostorg/graph/issues/268 #6132
• [boost] For Visual Studio, pass some values of settings.compiler.toolset to B2 #5119
• boost: header only boost::system #5051
• boost: use clang-win toolset when compiler=Visual Studio and compiler.toolset=ClangCL #4749
• Boost/1.72.0/mpi #3959

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[prince-chrismc]

Sorry, the build is only launched for Early Access Program users. You can request access writing in this issue.

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[conan-center-bot]

All green in build 11 (2191f2ac5bfcc6613517ae1d8348745105faf318):

• boost/1.69.0@:
  All packages built successfully! (All logs)

• boost/1.70.0@:
  All packages built successfully! (All logs)

• boost/1.71.0@:
  All packages built successfully! (All logs)

• boost/1.72.0@:
  All packages built successfully! (All logs)

• boost/1.73.0@:
  All packages built successfully! (All logs)

• boost/1.76.0@:
  All packages built successfully! (All logs)

• boost/1.75.0@:
  All packages built successfully! (All logs)

• boost/1.74.0@:
  All packages built successfully! (All logs)