abseil: inject CMAKE_SYSTEM_PROCESSOR if cross-building

[SpaceIm]

Specify library name and version: lib/1.0

When you cross-compile abseil, you can see this warning:

CMake Warning at source_subfolder/absl/copts/AbseilConfigureCopts.cmake:30 (message):
  Value of CMAKE_SYSTEM_PROCESSOR () is unknown and cannot be used to set
  ABSL_RANDOM_RANDEN_COPTS
Call Stack (most recent call first):
  source_subfolder/CMake/AbseilHelpers.cmake:18 (include)
  source_subfolder/CMakeLists.txt:73 (include)

Indeed, abseil has some logic based on CMAKE_SYSTEM_PROCESSOR: https://github.com/abseil/abseil-cpp/blob/20210324.2/absl/copts/AbseilConfigureCopts.cmake#L15-L32
When you cross-compile, CMAKE_SYSTEM_PROCESSOR is empty by default (and conan doesn't set this variable for you).

self.settings.arch should be sufficient.

---

• 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.

[ghost]

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

• abseil: add shared option + fix link to libm + drop few patch versions + modernize #6383

This message is automatically generated by https://github.com/ericLemanissier/conan-center-conflicting-prs so don't hesitate to report issues/improvements there.

[conan-center-bot]

All green in build 1 (4fe8a0db8db45d3180fbe1c34f3e40ece1c23e02):

• abseil/20200205@:
  All packages built successfully! (All logs)

• abseil/20200923.1@:
  All packages built successfully! (All logs)

• abseil/20200225.2@:
  All packages built successfully! (All logs)

• abseil/20200225.3@:
  All packages built successfully! (All logs)

• abseil/20200923@:
  All packages built successfully! (All logs)

• abseil/20210324.0@:
  All packages built successfully! (All logs)

• abseil/20210324.2@:
  All packages built successfully! (All logs)

• abseil/20200923.2@:
  All packages built successfully! (All logs)

• abseil/20200923.3@:
  All packages built successfully! (All logs)

• abseil/20210324.1@:
  All packages built successfully! (All logs)