AArch64: Use long for pointers in speech/srec classes

For storing pointers, long is used in speech/srec classes,
as native pointers can be 64-bit.

Note corresponding JNI files are in the external/srec project
under srec_jni directory.

Change-Id: Iacd10840e81f5acc3eb202424f83b49ae4eb23ab
Signed-off-by: Marcus Oakland <marcus.oakland@arm.com>
Signed-off-by: Ashok Bhat <ashok.bhat@arm.com>