Refactor: Simplify boolean expressions in llvm IR

[LegalizeAdulthood]

Summary

Simplify boolean expressions using true and false with clang-tidy

[dblaikie]

Looks good - committed in r233005

lib/IR/Instructions.cpp

if (DestTy->isIntegerTy()) {               // Casting to integral
     } else {                                   // Casting from something else
       return false;
     }
   } else if (DestTy->isVectorTy()) {         // Casting to vector
     return DestBits == SrcBits;
   } else if (DestTy->isPointerTy()) {        // Casting to pointer
     if (SrcTy->isPointerTy()) {                // Casting from pointer
       return true;
-    } else if (SrcTy->isIntegerTy()) {         // Casting from integral
-      return true;
-    } else {                                   // Casting from something else
-      return false;
-    }
+    } else
+      return SrcTy->isIntegerTy();             // Casting from integral
   } else if (DestTy->isX86_MMXTy()) {
     if (SrcTy->isVectorTy()) {
       return DestBits == SrcBits;       // 64-bit vector to MMX
     } else {
       return false;
     }
   } else {                                   // Casting to something else
     return false;