CMake cleanup: rm variable BA_PLATFORM, sort sections, require 64-bit platform.

Replaces !2503 (closed).

No more attempt to predict wheel name, just some cleanup.

cmake/BornAgain/Linux.cmake

@@ -12,24 +12,6 @@
 ##
 ##  ************************************************************************************************
 
-#... Get glibc version
-
-execute_process(
-    COMMAND ldd --version
-    RESULT_VARIABLE CMD_RESULT
-    OUTPUT_VARIABLE CMD_OUTPUT
-    ERROR_VARIABLE CMD_ERROR
-    OUTPUT_STRIP_TRAILING_WHITESPACE
-    ERROR_STRIP_TRAILING_WHITESPACE
-)
-if(NOT CMD_RESULT EQUAL 0)
-    message(FATAL_ERROR "Failed to execute ldd --version: ${CMD_ERROR}")
-endif()
-string(REGEX MATCH "GLIBC ([0-9]+)\\.([0-9]+).*" _ ${CMD_OUTPUT})
-set(LIBC_MAJOR ${CMAKE_MATCH_1})
-set(LIBC_MINOR ${CMAKE_MATCH_2})
-message(STATUS "Found libc version ${LIBC_MAJOR}.${LIBC_MINOR}")
-
 #... Set architecture variables
 
 if(${CMAKE_SYSTEM_PROCESSOR} STREQUAL x86_64)