[llvm] Use StringRef::consume_front (NFC)

Author: kazutakahirata

llvm/lib/Object/COFFModuleDefinition.cpp

@@ -97,10 +97,8 @@ class Lexer {
     }
     case '=':
       Buf = Buf.drop_front();
-      if (Buf.starts_with("=")) {
-        Buf = Buf.drop_front();
+      if (Buf.consume_front("="))
         return Token(EqualEqual, "==");
-      }
       return Token(Equal, "=");
     case ',':
       Buf = Buf.drop_front();

llvm/lib/Passes/StandardInstrumentations.cpp

@@ -1816,8 +1816,7 @@ std::string DotCfgDiffNode::getBodyContent() const {
     for (unsigned I = 0; I < 2; ++I) {
       SR[I] = Data[I]->getBody();
       // drop initial '\n' if present
-      if (SR[I][0] == '\n')
-        SR[I] = SR[I].drop_front();
+      SR[I].consume_front("\n");
       // drop predecessors as they can be big and are redundant
       SR[I] = SR[I].drop_until([](char C) { return C == '\n'; }).drop_front();
     }

llvm/lib/Support/FormatVariadic.cpp

@@ -77,8 +77,8 @@ formatv_object_base::parseReplacementItem(StringRef Spec) {
       assert(false && "Invalid replacement field layout specification!");
   }
   RepString = RepString.trim();
-  if (!RepString.empty() && RepString.front() == ':') {
-    Options = RepString.drop_front().trim();
+  if (RepString.consume_front(":")) {
+    Options = RepString.trim();
     RepString = StringRef();
   }
   RepString = RepString.trim();