Canonicalize header guards into a common format.

Add header guards to files that were missing guards. Remove #endif comments
as they don't seem common in LLVM (we can easily add them back if we decide
they're useful)

Changes made by clang-tidy with minor tweaks.

llvm-svn: 215558
diff --git a/llvm/lib/Target/PowerPC/PPCPerfectShuffle.h b/llvm/lib/Target/PowerPC/PPCPerfectShuffle.h
index 17b836d..8a1d680 100644
--- a/llvm/lib/Target/PowerPC/PPCPerfectShuffle.h
+++ b/llvm/lib/Target/PowerPC/PPCPerfectShuffle.h
@@ -12,6 +12,9 @@
 //
 //===----------------------------------------------------------------------===//
 
+#ifndef LLVM_LIB_TARGET_POWERPC_PPCPERFECTSHUFFLE_H
+#define LLVM_LIB_TARGET_POWERPC_PPCPERFECTSHUFFLE_H
+
 // 31 entries have cost 0
 // 292 entries have cost 1
 // 1384 entries have cost 2
@@ -6584,3 +6587,5 @@
   835584U,	// <u,u,u,u>: Cost 0 copy LHS
   0
 };
+
+#endif