Disable stack protector by default.

This option is disabled by default because it is known not to work
on FreeBSD 9.1 and for Linux -> Windows cross compiling using the
Debian MinGW-w64 tool chain.

Closes: https://github.com/erikd/libsndfile/issues/42
sndfile-convert.c : Add ability to specify endian-ness.

At the request of Jim Gray, allow endian-ness of output file to be
specified on the command line as:

    -endian=(little|big|cpu)

This is done before the call to sf_format_check() and may still
result in an error if the destination format does not support
the specified endian-ness.
src/flac.c : Fix seeking to offset 0 from end of file.

For FLAC files, (unlike WAV and others), seeking to the end of the
file using:

    file_length = sf_seek (file, 0, SEEK_END) ;

was failing because the underlying libFLAC was considering this as
an error condition. Work around this by detecting this in libsndfile
and doing the right thing.

Closes : https://github.com/erikd/libsndfile/issues/34
Add a couple of 'seek to end of file' tests.
.gitignore : Add generated file echo-install-dirs.
Add *.exe CLEANFILES in Makefile.am.
programs/common.[ch] : Add sfe_endian_name() etc functions.

Functions: sfe_endian_name(), sfe_container_name() and
sfe_codec_name().
programs/sndfile-convert.c : Improve error reporting.

Previous error reporting when the destination audio data format
wasn't supported by the container was inadequate.

Closes : https://github.com/erikd/libsndfile/issues/43
configure.ac : Add -Wmissing-declarations to CFLAGS.
src/sd2.c : Fix segfault in SD2 RSRC parser.

A specially crafted resource fork for an SD2 file can cause
the SD2 RSRC parser to read data from outside a dynamically
defined buffer. The data that is read is converted into a
short or int and used during further processing.

Since no write occurs, this is unlikely to be exploitable.

Bug reported by The Mayhem Team from Cylab, Carnegie Mellon
Univeristy. Paper is:
http://users.ece.cmu.edu/~arebert/papers/mayhem-oakland-12.pdf
programs/sndfile-convert.c : Add a -normalize command line argument.

Feature request by Tim Blechmann.

Closes : https://github.com/erikd/libsndfile/issues/23
configure.ac : Include a couple more -W flags.
tests/floating_point_test.tpl : Reduce tolerance of a couple of tests.

A couple of tests were failing when compiled with gcc-4.8 (and
gcc-snapshot/4.9.0 from Debian). The tests changed were for 32 bit
ALAC (test result changed from -186 to -181 dB signal-to-noise) and
for doubles (test results changed from -300 to -205 dB signal-to-noise).
configure.ac : Fix for current versions of autotools.

Patch from Cristian Rodriguez.
configure.ac : Drop -Wunreachable-code.

Warns on things like a break after a return in a switch statement.
Doesn't seem that useful a warning.
Fix a couple of warnings uncovered by the clang compiler.
Add file Scripts/clang-sanitize.sh.
src/ : Fix compiler warnings related to use of MAKE_MARKER macro.

Warnings were from the Clang compiler, complaining about things like
'255 << 24' overflowing a 32 bit integer. Solution was to change some
ints to uint32_t and an casts in the MAKE_MARKER macro itself.