Add a wrapper library to help testing without NPOTs.

* tests/tools/Makefile.am: Optionally build the
	libdisable-npots.la library depending on whether libdl was
	detected in the configure script. A helper script is also
	generated to setup the LD_PRELOAD.

	* tests/conform/Makefile.am: There are now two versions of the
	test-report and full-report rules. test-report-normal is the same
	as before and test-report-disable-npots runs the tests with the
	disable-npots wrapper script. The full-report rule runs both of
	them and displays two separate HTML files. The test-report rule
	just runs the normal version as before.

	* configure.ac: Add a test for libdl

	* tests/tools/disable-npots.sh.in: New file. Template for the
	helper script

	* tests/tools/disable-npots.c: New file

tests/tools/disable-npots.c

@@ -0,0 +1,84 @@
+/*
+ * This file can be build as a shared library and then used as an
+ * LD_PRELOAD to fake a system where NPOTs is not supported. It simply
+ * overrides glGetString and removes the extension strings.
+ */
+
+#include <GL/gl.h>
+#include <dlfcn.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <ctype.h>
+
+typedef const GLubyte * (* GetStringFunc) (GLenum name);
+
+static const char * const bad_strings[]
+= { "GL_ARB_texture_non_power_of_two",
+    "GL_ARB_texture_rectangle",
+    "GL_EXT_texture_rectangle",
+    NULL };
+
+const GLubyte *
+glGetString (GLenum name)
+{
+  const GLubyte *ret = NULL;
+  static void *gl_lib = NULL;
+  static GetStringFunc func = NULL;
+  static GLubyte *extensions = NULL;
+
+  if (gl_lib == NULL
+      && (gl_lib = dlopen ("libGL.so", RTLD_LAZY)) == NULL)
+    fprintf (stderr, "dlopen: %s\n", dlerror ());
+  else if (func == NULL
+	   && (func = (GetStringFunc) dlsym (gl_lib, "glGetString")) == NULL)
+    fprintf (stderr, "dlsym: %s\n", dlerror ());
+  else
+    {
+      ret = (* func) (name);
+
+      if (name == GL_EXTENSIONS)
+	{
+	  if (extensions == NULL)
+	    {
+	      if ((extensions = (GLubyte *) strdup ((char *) ret)) == NULL)
+		fprintf (stderr, "strdup: %s\n", strerror (errno));
+	      else
+		{
+		  GLubyte *dst = extensions, *src = extensions;
+
+		  while (1)
+		    {
+		      const char * const *str = bad_strings;
+		      GLubyte *end;
+
+		      while (isspace (*src))
+			*(dst++) = *(src++);
+
+		      if (*src == 0)
+			break;
+
+		      for (end = src + 1; *end && !isspace (*end); end++);
+
+		      while (*str && strncmp ((char *) src, *str, end - src))
+			str++;
+
+		      if (*str == NULL)
+			{
+			  memcpy (dst, src, end - src);
+			  dst += end - src;
+			}
+
+		      src = end;
+		    }
+
+		  *dst = '\0';
+		}
+	    }
+
+	  ret = extensions;
+	}
+    }
+
+  return ret;
+}