I have an ppc64le cross toolchain working on x86 which is powerpc64le-linux-gnu-gcc-5.0.
#grub-2.02_beta2_p20151217/configure --prefix=/usr --build=x86_64-pc-linux-gnu --host=powerpc64le-cros-linux-gnu --mandir=/usr/share/man --infodir=/usr/share/info --datadir=/usr/share --sysconfdir=/etc --localstatedir=/var/lib --disable-dependency-tracking --disable-silent-rules --docdir=/usr/share/doc/grub-2.02_beta2_p20151217-r10 --disable-werror --program-prefix= --libdir=/usr/lib --htmldir=/usr/share/doc/grub-2.02_beta2_p20151217-r10/html --disable-mm-debug --disable-grub-emu-usb --disable-device-mapper --disable-grub-mount --disable-nls --disable-grub-mkfont --disable-libzfs --disable-efiemu
.......
checking whether mbrtowc handles incomplete characters... (cached) guessing yes
checking whether mbrtowc works as well as mbtowc... (cached) guessing yes
checking whether wcrtomb return value is correct... guessing yes
checking whether iswcntrl works... guessing yes
checking for towlower... yes
checking for wctype_t... yes
checking for wctrans_t... yes
checking whether wctype is declared without a macro... yes
checking whether iswctype is declared without a macro... yes
checking whether wctrans is declared without a macro... yes
checking whether towctrans is declared without a macro... yes
checking whether wcwidth is declared... (cached) yes
checking whether wcwidth works reasonably in UTF-8 locales... (cached) yes
checking for stdint.h... (cached) yes
checking which extra warnings work... -Wextra -Wattributes -Wendif-labels -Winit-self -Wint-to-pointer-cast -Winvalid-pch -Wmissing-field-initializers -Wnonnull -Woverflow -Wvla -Wpointer-to-int-cast -Wstrict-aliasing -Wvariadic-macros -Wvolatile-register-var -Wpointer-sign -Wmissing-include-dirs -Wmissing-prototypes -Wmissing-declarations -Wformat=2
checking for powerpc64le-cros-linux-gnu-objcopy... powerpc64le-cros-linux-gnu-objcopy
checking for powerpc64le-cros-linux-gnu-strip... powerpc64le-cros-linux-gnu-strip
checking for powerpc64le-cros-linux-gnu-nm... powerpc64le-cros-linux-gnu-nm
checking for powerpc64le-cros-linux-gnu-ranlib... powerpc64le-cros-linux-gnu-ranlib
checking which extra warnings work... -Wextra -Wattributes -Wendif-labels -Winit-self -Wint-to-pointer-cast -Winvalid-pch -Wmissing-field-initializers -Wnonnull -Woverflow -Wvla -Wpointer-to-int-cast -Wstrict-aliasing -Wvariadic-macros -Wvolatile-register-var -Wpointer-sign -Wmissing-include-dirs -Wmissing-prototypes -Wmissing-declarations -Wformat=2
checking if compiling with clang... no
checking for options to get big-endian compilation... no
configure: error: could not force big-endian
....