tests/docker/run: don't source /etc/profile

The usual behaviour of /etc/profile is to set the default PATH for
users. This runs into problems when we have updated PATH in our
dockerfile e.g. to access a cross-compiler in a non-standard
location. It shouldn't be needed anyway as we inherit the env from the
image when it was setup.
Signed-off-by: NAlex Bennée <alex.bennee@linaro.org>
CC: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20170926133622.14991-1-alex.bennee@linaro.org>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: NFam Zheng <famz@redhat.com>

tests/docker/run

@@ -18,7 +18,6 @@ fi
 BASE="$(dirname $(readlink -e $0))"
 
 # Prepare the environment
-. /etc/profile
 export PATH=/usr/lib/ccache:$PATH
 
 if test -n "$J"; then