test: Replace "/proc/self/exe" with path to test binary

When tests are run under valgrind, /proc/self/exe points to valgrind,
not to the test binary. This results in failures for tests that need to
fork processes. Fix it by replacing "/proc/self/exe" with the path to
the test binary.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

test/file.cpp

@@ -180,7 +180,7 @@ protected:
 		}
 
 		/* Test size(). */
-		file.setFileName("/proc/self/exe");
+		file.setFileName(self());
 
 		if (file.size() >= 0) {
 			cerr << "File has valid size before open" << endl;
@@ -277,7 +277,7 @@ protected:
 		file.close();
 
 		/* Test mapping and unmapping. */
-		file.setFileName("/proc/self/exe");
+		file.setFileName(self());
 		file.open(File::OpenModeFlag::ReadOnly);
 
 		Span<uint8_t> data = file.map();