move `shellQuote` to implementation file

Summary: Fixing ODR violations...

Reviewed By: simpkins, yfeldblum

Differential Revision: D3875667

fbshipit-source-id: 0d8ec0b48e14fffb7e3e60c0e68e2576b2f58d1e

folly/Makefile.am

@@ -468,6 +468,7 @@ libfolly_la_SOURCES = \
 	Random.cpp \
 	SafeAssert.cpp \
 	SharedMutex.cpp \
+	Shell.cpp \
 	MicroLock.cpp \
 	Singleton.cpp \
 	SocketAddress.cpp \

folly/Shell.cpp

+/*
+ * Copyright 2016 Facebook, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <folly/Shell.h>
+
+namespace folly {
+
+std::string shellQuote(StringPiece argument) {
+  std::string quoted = "'";
+  for (auto c : argument) {
+    if (c == '\'') {
+      quoted += "'\\''";
+    } else {
+      quoted += c;
+    }
+  }
+  return quoted + "'";
+}
+
+} // folly

folly/Shell.h

@@ -27,6 +27,7 @@
 #include <string>
 #include <vector>
 
+#include <folly/Conv.h>
 #include <folly/Format.h>
 #include <folly/Range.h>
 
@@ -35,17 +36,7 @@ namespace folly {
 /**
  * Quotes an argument to make it suitable for use as shell command arguments.
  */
-std::string shellQuote(StringPiece argument) {
-  std::string quoted = "'";
-  for (auto c : argument) {
-    if (c == '\'') {
-      quoted += "'\\''";
-    } else {
-      quoted += c;
-    }
-  }
-  return quoted + "'";
-}
+std::string shellQuote(StringPiece argument);
 
 /**
   * Create argument array for `Subprocess()` for a process running in a