Merge pull request #7645 from alalek:cmake_arm_toolchain

platforms/linux/aarch64-gnu.toolchain.cmake

 set(CMAKE_SYSTEM_PROCESSOR aarch64)
-set(GCC_COMPILER_VERSION "4.8" CACHE STRING "GCC Compiler version")
+set(GCC_COMPILER_VERSION "" CACHE STRING "GCC Compiler version")
 set(GNU_MACHINE "aarch64-linux-gnu" CACHE STRING "GNU compiler triple")
 include("${CMAKE_CURRENT_LIST_DIR}/arm.toolchain.cmake")

platforms/linux/arm-gnueabi.toolchain.cmake

-set(GCC_COMPILER_VERSION "4.6" CACHE STRING "GCC Compiler version")
+set(GCC_COMPILER_VERSION "" CACHE STRING "GCC Compiler version")
 set(GNU_MACHINE "arm-linux-gnueabi" CACHE STRING "GNU compiler triple")
 include("${CMAKE_CURRENT_LIST_DIR}/arm.toolchain.cmake")

platforms/linux/arm.toolchain.cmake

@@ -33,6 +33,16 @@ if(NOT DEFINED CMAKE_CXX_COMPILER)
 else()
   #message(WARNING "CMAKE_CXX_COMPILER=${CMAKE_CXX_COMPILER} is defined")
 endif()
+if(NOT DEFINED CMAKE_LINKER)
+  find_program(CMAKE_LINKER NAMES ${GNU_MACHINE}${FLOAT_ABI_SUFFIX}-ld${__GCC_VER_SUFFIX} ${GNU_MACHINE}${FLOAT_ABI_SUFFIX}-ld)
+else()
+  #message(WARNING "CMAKE_LINKER=${CMAKE_LINKER} is defined")
+endif()
+if(NOT DEFINED CMAKE_AR)
+  find_program(CMAKE_AR NAMES ${GNU_MACHINE}${FLOAT_ABI_SUFFIX}-ar${__GCC_VER_SUFFIX} ${GNU_MACHINE}${FLOAT_ABI_SUFFIX}-ar)
+else()
+  #message(WARNING "CMAKE_AR=${CMAKE_AR} is defined")
+endif()
 
 if(NOT DEFINED ARM_LINUX_SYSROOT AND DEFINED GNU_MACHINE)
   set(ARM_LINUX_SYSROOT /usr/${GNU_MACHINE}${FLOAT_ABI_SUFFIX})