libjpeg-turbo: don't use chrpath

libjpeg-turbo: don't use chrpath

chrpath doesn't work on mingw32 binaries:

| `/build/tmp/work/x86_64-nativesdk-mingw32-w64-mingw32/nativesdk-libjpeg-turbo/3.0.1/image//usr/local/oe-sdk-hardcoded-buildpath/sysroots/x86_64-w64-mingw32/usr/bin/cjpeg.exe' probably isn't an ELF file.
| elf_open: Exec format error

Instead, use CMake variable to disable RPATH and avoid the
useless-rpaths QA error.

Signed-off-by: Samuli Piippo <samuli.piippo@qt.io>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>