Add a new (custom) macro AC_AGI_COMPILE to help with writing tests that use the

headers+libraries into runnable programs.  Hopefully this will solve all the
-dev package situations on Linux.

Originally committed to SVN as r2113.

acinclude.m4

@@ -1,3 +1,4 @@
+m4_include([m4macros/ac_agi.m4])
 m4_include([m4macros/ac_flag.m4])
 m4_include([m4macros/acx_pthread.m4])
 m4_include([m4macros/ax_check_gl.m4])

configure.in

@@ -148,6 +148,21 @@ fi
 AC_SUBST(GL_CFLAGS)
 AC_SUBST(GL_LIBS)
 
+#XXX: This needs to be fixed for OSX.
+AC_AGI_COMPILE([OpenGL], [opengl], [$GL_CFLAGS], [$GL_LIBS],[
+#include <GL/gl.h>
+#include <X11/Xlib.h>
+#include <GL/glx.h>
+int main(void) {
+  glXCreateContext(NULL, NULL, NULL, True);
+  glFinish();
+  return 0;
+}])
+
+if test "$agi_with_opengl" = "no"; then
+	AC_MSG_FAILURE([Please install a working OpenGL library.])
+fi
+
 PKG_CHECK_MODULES(FREETYPE, freetype2 >= 9.7.0,
   AC_DEFINE(WITH_FREETYPE2, 1, [Enable FreeType 2 support.]),
   [AC_MSG_FAILURE([aegisub requires >= FreeType2 2.1.9])])

m4macros/ac_agi.m4

@@ -0,0 +1,14 @@
+AC_DEFUN([AC_AGI_COMPILE],[
+  aegisub_save_LDFLAGS="$LDFLAGS"
+  aegisub_save_CPPFLAGS="$CPPFLAGS"
+  CPPFLAGS="$3"
+  LDFLAGS="$4"
+      AC_CACHE_CHECK(
+        [wether $1 works], [agi_with_$2],
+        [AC_COMPILE_IFELSE([$5],
+        [eval agi_with_$2="yes"],
+        [eval agi_with_$2="no"])
+        ])
+  CPPFLAGS="$aegisub_save_CPPFLAGS"
+  LDFLAGS="$aegisub_save_LDFLAGS"
+])