changed the implementation of SvPV() et al., breaking t/balloon.t, t/canvas2.t and t/photo.t on big-endian 64-bit architectures such as ppc64 and s390x because StringMatchGIF() no longer recognized GIF files.
This is because Tcl_GetByteArrayFromObj() was calling SvPV() with an int pointer instead of a correct STRLEN pointer, and the new implementation is more sensitive to this: it assigns the pointers as-is, resulting in the int pointer pointing at the wrong end of the 64-bit length.
Other functions taking a length pointer, at least Tcl_GetStringFromObj() already seem to do things correctly, so presumably this is not a systematic issue.
