THRIFT-1462 add more strict compiler flags

Patch: Roger Meier
diff --git a/compiler/cpp/Makefile.am b/compiler/cpp/Makefile.am
index 52b9c61..ee28d0c 100644
--- a/compiler/cpp/Makefile.am
+++ b/compiler/cpp/Makefile.am
@@ -93,7 +93,7 @@
                   src/generate/t_lua_generator.cc
 
 thrift_CPPFLAGS = -I$(srcdir)/src
-thrift_CXXFLAGS = -Wall
+thrift_CXXFLAGS = -Wall -Wextra -pedantic
 thrift_LDADD = @LEXLIB@ libparse.a
 
 libparse_a_CPPFLAGS = -I$(srcdir)/src