build: Drop old hack which is unneeded now

This hack is described in #8188. The current implementation was
introduced in #8315.

contrib/gitian-descriptors/gitian-linux.yml

@@ -20,8 +20,6 @@ packages:
 - "g++-8-riscv64-linux-gnu"
 - "gcc-8-riscv64-linux-gnu"
 - "binutils-riscv64-linux-gnu"
-- "g++-8-multilib"
-- "gcc-8-multilib"
 - "binutils-gold"
 - "git"
 - "pkg-config"
@@ -93,45 +91,11 @@ script: |
   create_per-host_faketime_wrappers "2000-01-01 12:00:00"
   export PATH=${WRAP_DIR}:${PATH}
 
-  EXTRA_INCLUDES_BASE=$WRAP_DIR/extra_includes
-  mkdir -p $EXTRA_INCLUDES_BASE
-
-  # x86 needs /usr/include/i386-linux-gnu/asm pointed to /usr/include/x86_64-linux-gnu/asm,
-  # but we can't write there. Instead, create a link here and force it to be included in the
-  # search paths by wrapping gcc/g++.
-
-  mkdir -p $EXTRA_INCLUDES_BASE/i686-pc-linux-gnu
-  rm -f $WRAP_DIR/extra_includes/i686-pc-linux-gnu/asm
-  ln -s /usr/include/x86_64-linux-gnu/asm $EXTRA_INCLUDES_BASE/i686-pc-linux-gnu/asm
-
-  for prog in gcc g++; do
-  rm -f ${WRAP_DIR}/${prog}
-  cat << EOF > ${WRAP_DIR}/${prog}
-  #!/usr/bin/env bash
-  REAL="$(which -a ${prog}-8 | grep -v ${WRAP_DIR}/${prog} | head -1)"
-  for var in "\$@"
-  do
-    if [ "\$var" = "-m32" ]; then
-      export C_INCLUDE_PATH="$EXTRA_INCLUDES_BASE/i686-pc-linux-gnu"
-      export CPLUS_INCLUDE_PATH="$EXTRA_INCLUDES_BASE/i686-pc-linux-gnu"
-      break
-    fi
-  done
-  \$REAL \$@
-  EOF
-  chmod +x ${WRAP_DIR}/${prog}
-  done
-
   cd bitcoin
   BASEPREFIX="${PWD}/depends"
   # Build dependencies for each host
   for i in $HOSTS; do
-    EXTRA_INCLUDES="$EXTRA_INCLUDES_BASE/$i"
-    if [ -d "$EXTRA_INCLUDES" ]; then
-      export HOST_ID_SALT="$EXTRA_INCLUDES"
-    fi
     make ${MAKEOPTS} -C ${BASEPREFIX} HOST="${i}"
-    unset HOST_ID_SALT
   done
 
   # Faketime for binaries