clang doesn't like -std=c++11 for Objective C files

[pdv]

Hi,

Build under OS X fails with:
  CXX      userinfo.o
  CXX      unicode.o
  OBJC     AppleSpeller.o
error: invalid argument '-std=c++11' not allowed with 'C/ObjC'

I moved the '-std=c++11' from the CPPFLAGS to the CXXFLAGS and defined 
OBJCFLAGS.

(patch included)

Regards,

Patrick De Visschere
diff --git a/config/lyxinclude.m4 b/config/lyxinclude.m4
index 81e91ca..5d7b666 100644
--- a/config/lyxinclude.m4
+++ b/config/lyxinclude.m4
@@ -366,8 +366,8 @@ if test x$GXX = xyes; then
       clang)
         dnl presumably all clang versions support c++11.
        dnl the deprecated-register warning is very annoying with Qt4.x right 
now.
-        AM_CPPFLAGS="$AM_CPPFLAGS -std=c++11"
-        AM_CXXFLAGS="$AM_CXXFLAGS -Wno-deprecated-register";;
+        AM_OBJCFLAGS="$AM_CXXFLAGS"
+        AM_CXXFLAGS="$AM_CXXFLAGS -std=c++11 -Wno-deprecated-register";;
       *)
         AS_CASE([$host], [*cygwin*],
                 [AM_CPPFLAGS="$AM_CPPFLAGS -std=gnu++11"],
diff --git a/configure.ac b/configure.ac
index 8ae7dcb..7b42065 100644
--- a/configure.ac
+++ b/configure.ac
@@ -241,6 +241,7 @@ VERSION_INFO="Configuration\n\
   Special build flags:     ${lyx_flags}\n\
   C++ Compiler:            ${CXX} ${CXX_VERSION}\n\
   C++ Compiler flags:      ${AM_CPPFLAGS} ${AM_CXXFLAGS}\n\
+  Obj C Compiler flags:    ${AM_CPPFLAGS} ${AM_OBJCFLAGS}\n\
   C++ Compiler user flags: ${CPPFLAGS} ${CXXFLAGS}\n\
   Linker flags:            ${AM_LDFLAGS}\n\
   Linker user flags:       ${LDFLAGS}\n\