SAMA5D4-EK: These configurations now use the fixed DRAM mapping for manipulating the page memory pool.

Add configuration to use the fixed DRAM mapping for the page pool (if available) instead of remapping dynamically to access L2 page tables and page data.  Also, add logic in address environment creation to initialize the shared data at the beginning of the .bss/.data process memory region.

When allocating a stack for a new process using the user-sapce allocator, need to select the address environment first

ELF relocations.  Some relocation types do not have a named symbol associated with them.  The design did not account for that case

Add logic that will permit us to build user libraries with different CFLAGS than kernel code.  This is needed because we need the -fno-common option when building ELF code to prevent SHN_COMMON relocations

SAM3X/Arduino Due: Fix typo in sam3x_periphclks.h; add SCLK definitions to board.h header file.  From Fabien Comte

SAM3X/Arduino Due: Fix typo in sam3x_periphclks.h; add SCLK definitions to board.h header file.  From Fabien Comte

SAMA5D4-EK: In kernel build with address environment, need logic to map user virtual addresses to physical addresses, and vice versa