Issue error if &=, |=, ^=, <<=, or >>= used with floats.

tests_errors/float-logical-1.ispc

@@ -0,0 +1,5 @@
+// First operand to binary operator "&" must be an integer or bool
+
+float foo(float a, float b) {
+    return a & b;
+}

tests_errors/float-logical.ispc

@@ -0,0 +1,5 @@
+// Illegal to use ^= operator with floating-point
+
+float foo(float a, float b) {
+    return a ^= b;
+}