Add the build_matrix.sh and build.sh scripts

Add the build_matrix.sh and build.sh scripts

Use them with Travis CI to build with less builders and save CI runtime.
This will currently run five builders: amd64, arm64, ppc64le, s390x and osx.

The build_matrix.sh script executes the matrix loops, exclude tests and
cleaning.
It conditionally builds libpcap running the build.sh script of libpcap.
It calls the build.sh script which runs one build with setup environment
variables: BUILD_LIBPCAP, REMOTE, CC, CMAKE, CRYPTO and SMB
(default: BUILD_LIBPCAP=no, REMOTE=no, CC=gcc, CMAKE=no, CRYPTO=no, SMB=no).
The matrix can be configured with environment variables
MATRIX_BUILD_LIBPCAP, MATRIX_REMOTE, MATRIX_CC, MATRIX_CMAKE, MATRIX_CRYPTO
and MATRIX_SMB
(default: MATRIX_BUILD_LIBPCAP='no yes', MATRIX_REMOTE='no yes',
MATRIX_CC='gcc clang', MATRIX_CMAKE='no yes', MATRIX_CRYPTO='no yes',
MATRIX_SMB='no yes').

These scripts can easily be updated to run new tests (32 bits builds,
sanitizers, coverage, etc).

They can be used locally for build tests or used with other CI systems.

Run examples:
./build_matrix.sh
MATRIX_BUILD_LIBPCAP=yes ./build_matrix.sh
MATRIX_CC=clang ./build_matrix.sh
CC=clang ./build.sh
CMAKE=yes ./build.sh
CC=clang CMAKE=yes CRYPTO=yes ./build.sh

Moreover:
Remove the old workaround PATH=$PATH...
Update the install directory prefix to /tmp/local.
Use vim modeline in the two shell scripts.