QStandardPaths: fall back to a default if PATH isn't set

Change 28666d167aa8e602c0bea25ebc4d51b55005db13 simplified
QProcess::start{Process,Detached} by using findExecutable() instead of
using execvp, but this introduced an unintended side effect when the
PATH environment variable isn't set. It turns out that most libc have a
default fallback in that situation, which we didn't apply.

This commit applies the default directly to findExecutable(), which
seems sensible.

[ChangeLog][QtCore][QProcess] Fixed a regression that made QProcess be
unable to find executables when the PATH environment variable on some
Unix systems wasn't set. This behavior should not be relied upon since
many systems do not have sensible fallback values for PATH.

[ChangeLog][QtCore][QStandardPaths] findExecutable() will now apply the
default value for the PATH environment variable (as returned by the
POSIX confstr(3) function or found in <paths.h>) if the variable
isn't set in the environment.

Task-number: QTBUG-65076
Change-Id: I9407dcf22de6407c83b5fffd14feda6c1f509210
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@qt.io>
Reviewed-by: David Faure <david.faure@kdab.com>

0 files changed, 0 insertions, 0 deletions