fixes issue 1091

Documented the requirement that those calling configure_DynamoRIO_*() from
a function scope must first call configure_DynamoRIO_global() from global
scope ahead of time.  I tried various methods of using CACHE INTERNAL FORCE
to set these vars globally but I could not get anything to work with all
generators.

Adds configure_DynamoRIO_global() to the samples CMakeLists.txt.

git-svn-id: https://dynamorio.googlecode.com/svn/trunk@1951 49cc7528-f6fd-11dd-9d1a-b59b2e1864b6
i#1094: Don't search NULL rpaths and fix Linux impl of GetFullPathName()

We can't do an rpath search if we don't have an initial dependent module
that might contain rpaths.  This is just a missing NULL check.

realpath() checks for existence and resolves symlinks, which is not
equivalent to the Windows GetFullPathName() behavior.  The new
implementation simply concatenates the CWD with the relative path minus
any leading ./.

Fixes issue 1094.

Review URL: https://codereview.appspot.com/7395061

git-svn-id: https://dynamorio.googlecode.com/svn/trunk@1952 49cc7528-f6fd-11dd-9d1a-b59b2e1864b6
i#1097: Always override DYNAMORIO_OPTIONS on execve

This fixes the behavior change from the new Linux drrun frontend, which
does not set DYNAMORIO_OPTIONS in the environment.  It also prevents the
app from changing the options and then calling execve() on itself to
escape DR, which is a regression since DR was open sourced.

Fixes issue 1097.

Review URL: https://codereview.appspot.com/7388063

git-svn-id: https://dynamorio.googlecode.com/svn/trunk@1953 49cc7528-f6fd-11dd-9d1a-b59b2e1864b6
i#1077: Avoid interpreting back_from_native

This adds a check to dispatch() to see if we're about to interpret one
of the back_from_native return stubs.  If we hit one of these stubs, we
pop the appropriate app return address from the native return stack and
continue interpreting at that PC.

Review URL: https://codereview.appspot.com/7407048

git-svn-id: https://dynamorio.googlecode.com/svn/trunk@1954 49cc7528-f6fd-11dd-9d1a-b59b2e1864b6