Failed to build gcc-5.3.0

When running make, I get this error. What went wrong? I'm running Debian 9.9 under Windows Subsystem for Linux.
You can now run IASL ACPI compiler from /root/heads/build/coreboot-4.8.1/util/crossgcc/xgcc.
make[2]: Leaving directory '/root/heads/build/coreboot-4.8.1'
#echo '******* Building crossgcc-arm (this might take a while) ******'
#/root/heads/build/make-4.2.1/make -C "/root/heads/build/coreboot-4.8.1" crossgcc-arm
2019-08-16 12:07:50+02:00 CONFIG coreboot
git clone https://github.com/GregorR/musl-cross "/root/heads/build/musl-cross-git"
Cloning into '/root/heads/build/musl-cross-git'...
remote: Enumerating objects: 796, done.
remote: Total 796 (delta 0), reused 0 (delta 0), pack-reused 796
Receiving objects: 100% (796/796), 289.34 KiB | 158.00 KiB/s, done.
Resolving deltas: 100% (499/499), done.
cd /root/heads/build/musl-cross-git && git submodule update --init --checkout
if [ -r patches/musl-cross.patch ]; then ( cd /root/heads/build/musl-cross-git ; patch -p1 ) < patches/musl-cross.patch || exit 1 ; fi
patching file config.sh
if [ -d patches/musl-cross ] && [ -r patches/musl-cross ] ; then for patch in patches/musl-cross/*.patch ; do echo "Applying patch file : $patch " ; ( cd /root/heads/build/musl-cross-git ; patch -p1 ) < $patch || exit 1 ; done ; fi
2019-08-16 12:08:16+02:00 CONFIG musl-cross
2019-08-16 12:08:16+02:00 MAKE musl-cross
tail /root/heads/build/log/musl-cross.log
-----
config.status: executing libtool commands
configure: summary of build options:

  Version:           GNU MP 6.1.0
  Host type:         none-unknown-linux-gnu
  ABI:               standard
  Install prefix:    /root/heads/crossgcc/x86_64-linux-musl
  Compiler:          gcc
  Static libraries:  yes
  Shared libraries:  no

make[4]: Leaving directory '/root/heads/build/musl-cross-git/gcc-5.3.0/build1'
make[3]: *** [Makefile:859: all] Error 2
make[3]: Leaving directory '/root/heads/build/musl-cross-git/gcc-5.3.0/build1'
+ die Failed to build gcc-5.3.0
+ echo Failed to build gcc-5.3.0
Failed to build gcc-5.3.0
+ exit 1
make[2]: *** [Makefile:2: ../../crossgcc/x86_64-linux-musl/bin/x86_64-musl-linux-gcc] Error 1
make[2]: Leaving directory '/root/heads/build/musl-cross-git'
make[1]: *** [Makefile:378: /root/heads/build/musl-cross-git/.build] Error 1
make[1]: Leaving directory '/root/heads'
Makefile:584: recipe for target 'all' failed
make: *** [all] Error 2
root@LAPTOP:~/heads#
linuxboot / heads-wiki

Failed to build gcc-5.3.0 #29
