libphobos: Fix SIGBUS in read_encoded_value_with_base on sparc-sun-solaris (PR98584)

Instead of unsafe pointer dereferencing, use memcpy() to read encoded
values from memory.  The function `read_encoded_value' has been updated
to accept a ref parameter, this simplifies handling of the pointer to
memory needing to be read.

libphobos/ChangeLog:

	PR d/98584
	* libdruntime/gcc/deh.d (scanLSDA): Update calls to read_uleb128 and
	read_encoded_value.
	(actionTableLookup): Update calls to read_sleb128 and
	read_encoded_value_with_base.
	* libdruntime/gcc/unwind/pe.d (read_uleb128): Update signature.
	(read_sleb128): Update signature.
	(read_unaligned): New function.
	(read_encoded_value_with_base): Update signature.  Call read_unaligned
	instead of unsafe pointer dereferencing.
	(read_encoded_value): Update signature.