Bump atomic_ops version

* README.md: Bump version to 7.5.0.
* configure.ac: Likewise.
* src/atomic_ops/ao_version.h (AO_VERSION_MINOR): Likewise.
Update emails/links due to project site transition

* AUTHORS: Update email.
* README.md: Update links to BDWGC/libatomic_ops site.
* doc/README_stack.txt: Likewise.
* README.md: Update mailing list info.
* configure.ac: Likewise.
Removed unnecessary "an"
Merge pull request #8 from badboy/patch-1

Fix a typo in doc/README.txt (remove redundant "an" article)
Update ChangeLog file
Restore contribution info in ChangeLog for authors not listed in git log
(deleted in commit 36a9c66)

* ChangeLog (7.0, 1.0): Add information about contribution of persons
mentioned in AUTHORS but not recorded in git log.
* src/atomic_ops/sysdeps/gcc/cris.h: Move contribution information
from comment to ChangeLog.
Fix makefile preventing AO_pause undefined in libatomic_ops_gpl

* src/Makefile.am (libatomic_ops_gpl_la_LIBADD): New dependency.
.gitignore: Ignore tests/.libs (generated if configure --enable-shared)
.gitignore: Ignore .dirstamp
Fix missing casts to match printf format specifier in test_atomic

* tests/test_atomic.c (test_and_set_thr): Add missing casts to long
for locked_counter (which is unsigned long) to match printf format
specifier.
Eliminate 'variable set but not used' Cppcheck warnings in test_stack

* tests/test_stack.c (run_one_test): Define "j" local variable only
if VERBOSE.
* tests/test_stack.c (main): Do not define "sum" local variable (and
don not compute the sum) if NO_TIMES.
Merge pull request #3 from ivmai/master

Updates from ivmai