Drop CLANGBUILD in addition to CLANGDIR?

Quoting Freenode #libreoffice-dev:

> Feb 24 09:37:55 <sberg> tml_, you're using our Clang plugins against some distro-provided Clang, 
> right? do you need to specify different values for CLANGBUILD and CLANGDIR?  (because with my self-built 
> Clang I always need to specify the same value for both anyway, so I wonder we can get rid of one of them)
> Feb 24 09:38:44 <tml_> sberg: yep, against the openSUSE 12.3 -provided clang. no, I don't set any 
> such env vars
> Feb 24 09:39:32 <ahunt> sberg: On Suse I've never had to specify anything except CC and CXX, on 
> debian I had to set CLANGBUIL and CLANGDIR (but they were the same), and also had to add a symlink so 
> that the clang binary itself was also within the CLANGBUILD/CLANGDIR specified directory.
> Feb 24 09:39:48 <sberg> tml_, i.e., both are set to the /usr default in config_host.mk for you?
> Feb 24 09:40:01 <tml_> yep
> Feb 24 09:41:05 <sberg> ahunt, tml_, ok, so looks like we can live with just one var; I'll put it 
> up on the ML and if nobody objects will remove one of the two

That is, anybody any objections against committing the below patch to 
master?

Stephan

> diff --git a/compilerplugins/Makefile-clang.mk b/compilerplugins/Makefile-clang.mk
> index 5d09346..2c57f40 100644
> --- a/compilerplugins/Makefile-clang.mk
> +++ b/compilerplugins/Makefile-clang.mk
> @@ -21,7 +21,7 @@ CLANGCXXFLAGS=-O2 -Wall -Wextra -g
>  # Clang headers require these.
>  CLANGDEFS=-D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -fno-rtti
>  # All include locations needed.
> -CLANGINCLUDES=-isystem $(CLANGDIR)/include -isystem $(CLANGDIR)/tools/clang/include -isystem 
> $(CLANGBUILD)/include -isystem $(CLANGBUILD)/tools/clang/include
> +CLANGINCLUDES=-isystem $(CLANGDIR)/include -isystem $(CLANGDIR)/tools/clang/include
>
>  # Clang/LLVM libraries are intentionally not linked in, they are usually built as static 
> libraries, which means the resulting
>  # plugin would be big (even though the clang binary already includes it all) and it'd be necessary 
> to explicitly specify
> @@ -93,7 +93,7 @@ $(CLANGOUTDIR)/plugin.so: $(CLANGOBJS)
>                         -Wl$(CLANG_COMMA)-undefined -Wl$(CLANG_COMMA)suppress)
>
>  # Clang most probably doesn't maintain binary compatibility, so rebuild when clang changes.
> -$(CLANGOUTDIR)/clang-timestamp: $(CLANGBUILD)/bin/clang
> +$(CLANGOUTDIR)/clang-timestamp: $(CLANGDIR)/bin/clang
>         $(QUIET)touch $@
>
>  # vim: set noet sw=4 ts=4:
> diff --git a/config_host.mk.in b/config_host.mk.in
> index 697d788..a9caf50 100644
> --- a/config_host.mk.in
> +++ b/config_host.mk.in
> @@ -51,7 +51,6 @@ export CC=@CC@
>  export CDR_CFLAGS=$(gb_SPACE)@CDR_CFLAGS@
>  export CDR_LIBS=$(gb_SPACE)@CDR_LIBS@
>  @x_CFLAGS@ export CFLAGS=@CFLAGS@
> -export CLANGBUILD=@CLANGBUILD@
>  export CLANGDIR=@CLANGDIR@
>  export CLUCENE_CFLAGS=$(gb_SPACE)@CLUCENE_CFLAGS@
>  export CLUCENE_LIBS=$(gb_SPACE)@CLUCENE_LIBS@
> diff --git a/configure.ac b/configure.ac
> index 092d4e1..fcfe9f9 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -5656,18 +5656,13 @@ if test "$COM_GCC_IS_CLANG" = "TRUE"; then
>          if test -z "$CLANGDIR"; then
>              CLANGDIR=/usr
>          fi
> -        dnl The build directory (different from CLANGDIR if using a Clang out-
> -        dnl of-source build):
> -        if test -z "$CLANGBUILD"; then
> -            CLANGBUILD=/usr
> -        fi
>          AC_LANG_PUSH([C++])
>          save_CPPFLAGS=$CPPFLAGS
>          save_CXX=$CXX
>          # compiler plugins must be built with "native" bitness of clang
>          # because they link against clang libraries
>          CXX=`echo $CXX | sed -e s/-m64// -e s/-m32//`
> -        CPPFLAGS="$CPPFLAGS -I$CLANGDIR/include -I$CLANGDIR/tools/clang/include -I$CLANGBUILD/include 
> -I$CLANGBUILD/tools/clang/include -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS"
> +        CPPFLAGS="$CPPFLAGS -I$CLANGDIR/include -I$CLANGDIR/tools/clang/include 
> -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS"
>          AC_CHECK_HEADER(clang/AST/RecursiveASTVisitor.h,
>              [COMPILER_PLUGINS=TRUE],
>              [
> @@ -5689,7 +5684,6 @@ else
>  fi
>  AC_SUBST(COMPILER_PLUGINS)
>  AC_SUBST(CLANGDIR)
> -AC_SUBST(CLANGBUILD)
>
>  # Plugin to help linker.
>  # Add something like LD_PLUGIN=/usr/lib64/LLVMgold.so to your autogen.input.