Fix redundant inline operators

inline is not required on member methods.  Clang-tidy has a check for
this.  Enable the check and fix the two bad usages.

Tested: Code compiles.

Change-Id: I3115b7c0c4005e1082e0005b818fbe6569511f49
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/include/multipart_parser.hpp b/include/multipart_parser.hpp
index 924ee8d..9d55f3a 100644
--- a/include/multipart_parser.hpp
+++ b/include/multipart_parser.hpp
@@ -239,7 +239,7 @@
         return static_cast<char>(c | 0x20);
     }
 
-    inline bool isBoundaryChar(char c) const
+    bool isBoundaryChar(char c) const
     {
         return boundaryIndex[static_cast<unsigned char>(c)];
     }