nspr failed on x86_64 dockyard-devel (c64.arklinux.org)

nspr failed to build on x86_64 for dockyard-devel.
Last 250 lines of build log:

warning: user arklinux does not exist - using root
Installing nspr-4.6.7-1ark.src.rpm
Building target platforms: x86_64
Building for target x86_64
Executing(%prep): /bin/sh -e /var/tmp/rpm-tmp.71040
+ umask 022
+ cd /build-nspr-x86_64/BUILD
+ cd /build-nspr-x86_64/BUILD
+ rm -rf nspr-4.6.7
+ tar -xf /usr/src/ark/SOURCES/nspr-4.6.7.tar.lz
+ cd nspr-4.6.7
++ /usr/bin/id -u
+ '[' 0 = 0 ']'
+ /bin/chown -Rhf root .
++ /usr/bin/id -u
+ '[' 0 = 0 ']'
+ /bin/chgrp -Rhf root .
+ /bin/chmod -Rf a+rX,g-w,o-w .
+ exit 0
Executing(%build): /bin/sh -e /var/tmp/rpm-tmp.19440
+ umask 022
+ cd /build-nspr-x86_64/BUILD
+ cd nspr-4.6.7
+ ./mozilla/nsprpub/configure --prefix=/usr --libdir=/usr/lib64 --enable-64bit --includedir=/usr/include/nspr '--enable-optimize=-O2 -fomit-frame-pointer -fweb -frename-registers' --disable-debug
creating cache ./config.cache
checking host system type... x86_64-unknown-linux-gnu
checking target system type... x86_64-unknown-linux-gnu
checking build system type... x86_64-unknown-linux-gnu
checking for whoami... /usr/bin/whoami
checking for c++... c++
checking whether the C++ compiler (c++  ) works... no
configure: error: installation or configuration problem: C++ compiler cannot create executables.
error: Bad exit status from /var/tmp/rpm-tmp.19440 (%build)


RPM build errors:
    user arklinux does not exist - using root
    Bad exit status from /var/tmp/rpm-tmp.19440 (%build)