Make Driver::link and LinkingContext::validate return true on success.

This patch inverts the return value of these functions, so that they return
"true" on success and "false" on failure. The meaning of boolean return value
was mixed in LLD; for example, InputGraph::validate() returns true on success.
With this patch they'll become consistent.

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1748

llvm-svn: 191341
diff --git a/lld/lib/ReaderWriter/CoreLinkingContext.cpp b/lld/lib/ReaderWriter/CoreLinkingContext.cpp
index 8f89f1d..fdc56ec 100644
--- a/lld/lib/ReaderWriter/CoreLinkingContext.cpp
+++ b/lld/lib/ReaderWriter/CoreLinkingContext.cpp
@@ -272,7 +272,7 @@
 CoreLinkingContext::CoreLinkingContext() {}
 
 bool CoreLinkingContext::validateImpl(raw_ostream &diagnostics) {
-  return false;
+  return true;
 }
 
 void CoreLinkingContext::addPasses(PassManager &pm) const {