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C and C++ library changes between ARM Compiler v4.1 build 561 and v4.1 Patch 3 or later

Various changes have been made to the ARMC C and C++ library in ARM Compiler toolchain v4.1 Patch 3.

The new implementation of alloca() allocates memory on the stack and not on the heap. This does not cause compatibility problems with software that assumes the old heap-based implementation of alloca(). However, such software might contain operations that are no longer required, such as implementing __user_perthread_libspace for the alloca state that is no longer used.