fixes issue #711

specifying a multiword CC, e.g., CC='gcc -m32', would cause the failure
under dash

reported in
https://bugs.gentoo.org/show_bug.cgi?id=498136

patch by floppymaster at gmail dot com

Change-Id: I2ba246f765646161538622739961ec0f6c2d8c2d

clang on macosx does not support -Wunused-but-set-variable; adding the flag
causes additional warnings about the flag. As a more generalized fix, use
-Werror when checking compiler flag support in order to avoid using
unsupported warning flags.

Change-Id: I2529862e211f880d56491eac3b9fa90fff1aa5c3

Change-Id: I736f5753ff42782bbb2a401d2c28cd755fa2f8da

* changes:
  configure: add a test for configured source dir
  Makefile: add distclean target

Change-Id: I7126e4b36994020cc656d046d10df5d6a6c53e66

Change-Id: I76e39f7c5545ba4e0cd537f530c574531356e94a

Removes some unused variables and assignments

Change-Id: I228f43d658ce50237d65ce8dc8ab2ccf0a0b21ca

clang reports gcc-4.2.1 in e.g., 3.3, 3.4; add a specific clang version
check for _mm256_broadcastsi128_si256

fixes issue #720

Change-Id: I5c8e3c27fdea05d8a5b050e8cb74894b595f4709

Change-Id: I03451c88536bc498edddbe0cd9773ff79da085c2

fixes a warning in vs9/x64 related to ceil()

Change-Id: Ic4bde9d0b7e961546dbe304de74aa37fc02fcf94

Change-Id: I2c117ddeae3da5119f549b036a5699a8092819d3

prevents out of tree build failures when the source tree has already
been configured; modeled after a similar check in autoconf

Change-Id: I627eb7243576f4d753141dfcb4ed4e34544d03a7

wipes out configure generated files

Change-Id: I55d5865b84c6dfc19f13011e66e3483c54bf6a15

Change-Id: Ibabd8440ff5c9dd7f300f317e2c9d50e8e84aab9

Stop configuration and report an error when make is not available.

Change-Id: I599a4c43386e3657748d5b875afb235701e6b57f