Description:
Because /usr/lib/distcc/bin/c++ does not exist, makepkg with distcc did not compile faster for c++ files without burning the main machine. The attached patch resolves this issue by creating a symlink.

Additional info:
* distcc 3.1-6


Steps to reproduce:
--- contents of ~/.makepkg.conf ---
DISTCC_HOSTS="10.0.0.1/12 10.0.0.2/12"

DISTCC_HOSTS=$(
for host in $DISTCC_HOSTS; do
if nc -z ${host%/*} 3632; then
echo "$host"
fi
done
)

# if there are farms available
if [ -n "$DISTCC_HOSTS" ]; then
DISTCC_HOSTS="localhost/4 $DISTCC_HOSTS"
for ((i=0; i<${#BUILDENV[@]}; i++)); do
if [[ ${BUILDENV[i]} == !distcc ]]; then
BUILDENV[i]=distcc
fi
done
MAKEFLAGS="-j$(DISTCC_HOSTS="$DISTCC_HOSTS" distcc -j)"
fi
---
(change DISTCC_HOSTS as needed)

Next, get a package that uses C++, I encountered this with "akonadi-google-git" from AUR.

$ makepkg
...
-- The C compiler identification is GNU 4.7.1
-- The CXX compiler identification is GNU 4.7.1
-- Check for working C compiler: /usr/lib/distcc/bin/gcc
-- Check for working C compiler: /usr/lib/distcc/bin/gcc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
...

Note the "Check for working CXX compiler: /usr/bin/c++" line.