possible fix for obscure GCC build error

Dockerfile

@@ -13,10 +13,12 @@ ENV REVNUM=$REVNUM
 ARG PYTHON_VERSION=39
 ARG TRIM=cspp
 ENV PORTABLESHELLB3=true
-ENV MAKEFLAGS=-j40
 
 FROM setup as compiler
+ENV MAKEFLAGS=-j8
 RUN ./shallbethree.sh mk_gcc12
+
+ENV MAKEFLAGS=-j16
 ARG LINUXCPUFLAGS="-march=ivybridge -fPIC"
 ENV LINUXCPUFLAGS="${LINUXCPUFLAGS}"
 # numcodecs will break on avx2 build when ivybridge arch is forced

ShellB3/shallbethree.sh

@@ -7247,7 +7247,11 @@ mk__gcc() {
     NAMESRCPATH="gcc src/sys/gcc-${GCCVER}.tar.* gcc-${GCCVER}"
   fi
-  CXXFLAGS="$(omitparameter -stdlib=libc++ 0 ${CXXFLAGS})" CPPFLAGS="$(omitparameter -stdlib=libc++ 0 ${CPPFLAGS}) $( isDarwin && echo -DHAVE_FCNTL_H=1 -DHAVE_SPAWN_H=1)" \
+  # https://github.com/riscv-collab/riscv-gnu-toolchain/issues/860
+  unset LIBRARY_PATH
+  export LD_LIBRARY_PATH="$BASE/lib:$BASE/lib64:$LD_LIBRARY_PATH"
+
+  CXXFLAGS="$(omitparameter -stdlib=libc++ 0 ${CXXFLAGS})" CPPFLAGS="$(omitparameter -stdlib=libc++ 0 ${CPPFLAGS}) $( isDarwin && echo -DHAVE_FCNTL_H=1 -DHAVE_SPAWN_H=1)" \ 
     _configure_make_install ${NAMESRCPATH} --with-gmp=${BASE} --with-mpfr=${BASE} \
       --with-mpc=${BASE} --bindir=${BASE}/sysbin --disable-libgcj --with-isl=${BASE} --enable-checking=release \
       --disable-multilib --enable-languages=${LANGS} ${EXTRAPARMS} "$@"