Fix test-0cf405b0 for newer versions of glibc.

Newer versions of glibc apparently enforce argv to contain at least one
argument, regardless of what what passed to execlp(). This behavioral
change resulted in test-0cf405b0 performing an endless loop.

This commit addresses this problem by setting an environment variable to
indicate, whether the execlp() call has already been performed.

test/test-0cf405b0.c

@@ -1,12 +1,13 @@
 #include <unistd.h> /* execlp(2), */
-#include <stdlib.h> /* exit(3), */
+#include <stdlib.h> /* exit(3), getenv(3), setenv(3)*/
 #include <string.h> /* strcmp(3), */
 
 int main(int argc, char *argv[])
 {
-	if (argc == 0) //strcmp(argv[0], "/proc/self/exe") == 0)
+	if (getenv("PROC_SELF_EXE") != NULL)
 		exit(EXIT_SUCCESS);
 
+	setenv("PROC_SELF_EXE", "1", 1);
 	execlp("/proc/self/exe", NULL);
 	exit(EXIT_FAILURE);
 }