progs/fpglsl: Fix GLSL compilation failures on Mac OS X.

progs/fpglsl/for.glsl

@@ -6,6 +6,6 @@ void main() {
     for (i = 0; i < KernelSizeInt; ++i) {
 	sum.g += 0.25;
     }
-    sum.a = 1;
+    sum.a = 1.0;
     gl_FragColor = sum;
 }

progs/fpglsl/forbreak.glsl

@@ -8,6 +8,6 @@ void main() {
         if (i > 0)
            break;
     }
-    sum.a = 1;
+    sum.a = 1.0;
     gl_FragColor = sum;
 }