mysql-connector-c: fix usage with static libc++

[ericLemanissier]

Specify library name and version: mysql-connector-c/*

• I've read the guidelines for contributing.
• I've followed the PEP8 style guides for Python code in the recipes.
• I've used the latest Conan client version.
• I've tried at least one configuration locally with the
  conan-center hook activated.

[conan-center-bot]

Failure in build 1 (b19c813b15593093ba5083a4c5b896dbf5886491):

• mysql-connector-c/6.1.11@:
  CI failed to create some packages (All logs)

  Logs for packageID 516428e74bce45838ba1b55e9915ebbdd96563b3:

  [settings]
  arch=x86_64
  arch_build=x86_64
  build_type=Release
  compiler=apple-clang
  compiler.libcxx=libc++
  compiler.version=12.0
  os=Macos
  os_build=Macos
  [options]
  mysql-connector-c:shared=True
  

  ********************************************************************************
  Configuration:
  [settings]
  arch=x86_64
  arch_build=x86_64
  build_type=Release
  compiler=apple-clang
  compiler.libcxx=libc++
  compiler.version=12.0
  os=Macos
  os_build=Macos
  [options]
  mysql-connector-c:shared=True
  [build_requires]
  [env]
  
  mysql-connector-c/6.1.11: Forced build from source
  Installing package: mysql-connector-c/6.1.11
  Requirements
      mysql-connector-c/6.1.11 from local cache - Cache
      openssl/1.0.2u from 'conan-center' - Cache
      zlib/1.2.11 from 'conan-center' - Cache
  Packages
      mysql-connector-c/6.1.11:516428e74bce45838ba1b55e9915ebbdd96563b3 - Build
      openssl/1.0.2u:88955cec2844f731470e07bd44ce5a3a24ec88b7 - Cache
      zlib/1.2.11:647afeb69d3b0a2d3d316e80b24d38c714cc6900 - Cache
  
  Installing (downloading, building) binaries...
  zlib/1.2.11: Already installed!
  [HOOK - conan-center.py] post_package_info(): [CMAKE FILE NOT IN BUILD FOLDERS (KB-H019)] OK
  [HOOK - conan-center.py] post_package_info(): [LIBRARY DOES NOT EXIST (KB-H054)] OK
  openssl/1.0.2u: Already installed!
  [HOOK - conan-center.py] post_package_info(): [CMAKE FILE NOT IN BUILD FOLDERS (KB-H019)] OK
  [HOOK - conan-center.py] post_package_info(): [LIBRARY DOES NOT EXIST (KB-H054)] OK
  mysql-connector-c/6.1.11: Copying sources to build folder
  mysql-connector-c/6.1.11: Building your package in /Users/jenkins/w/BuildSingleReference@2/.conan/data/mysql-connector-c/6.1.11/_/_/build/516428e74bce45838ba1b55e9915ebbdd96563b3
  mysql-connector-c/6.1.11: Generator cmake created conanbuildinfo.cmake
  [HOOK - conan-center.py] pre_build(): [FPIC MANAGEMENT (KB-H007)] 'fPIC' option not found
  [HOOK - conan-center.py] pre_build(): [FPIC MANAGEMENT (KB-H007)] OK
  mysql-connector-c/6.1.11: Calling build()
  mysql-connector-c/6.1.11: 
  [HOOK - conan-center.py] post_package_info(): WARN: [LIBRARY DOES NOT EXIST (KB-H054)] Component openssl::openssl libdir "lib" does not contain any declared library
  mysql-connector-c/6.1.11: WARN: Build folder is dirty, removing it: /Users/jenkins/w/BuildSingleReference@2/.conan/data/mysql-connector-c/6.1.11/_/_/build/516428e74bce45838ba1b55e9915ebbdd96563b3
  mysql-connector-c/6.1.11: ERROR: Package '516428e74bce45838ba1b55e9915ebbdd96563b3' build failed
  mysql-connector-c/6.1.11: WARN: Build folder /Users/jenkins/w/BuildSingleReference@2/.conan/data/mysql-connector-c/6.1.11/_/_/build/516428e74bce45838ba1b55e9915ebbdd96563b3
  ERROR: mysql-connector-c/6.1.11: Error in build() method, line 72
  	cmake = self._configure_cmake()
  while calling '_configure_cmake', line 45
  	self._cmake.definitions["REQUIRE_STDCPP"] = self._stdcpp_library
  	AttributeError: 'MysqlConnectorCConan' object has no attribute '_stdcpp_library'
  

---

^{Note: To save resources, CI tries to finish as soon as an error is found. For this reason you might find that not all the references have been launched or not all the configurations for a given reference. Also, take into account that we cannot guarantee the order of execution as it depends on CI workload and workers availability.}

[conan-center-bot]

All green in build 2 (5a9c958dd421a864e86232afd163a746d4a0f65f):

• mysql-connector-c/6.1.11@:
  All packages built successfully! (All logs)

[ericLemanissier]

Friendly ping @uilianries, is it possible to review this one before it gets stale ? It's the same change you approved on #5103

[prince-chrismc]

Don't feel bad 🤗 It's not just this PR 💟 it's just been slow 🐢

There's a huge backlog on prince-chrismc/conan-center-index-pending-review#1

🤓 Please Review!

There are 20 pull requests currently under way 👀

Which is a lot by comparison to january/february