Overhauled llvm/clang docs builds. Closes PR6613.

NOTE: 2nd part changeset for cfe trunk to follow.

*** PRE-PATCH ISSUES ADDRESSED

- clang api docs fail build from objdir
- clang/llvm api docs collide in install PREFIX/
- clang/llvm main docs collide in install
- clang/llvm main docs have full of hard coded destination
  assumptions and make use of absolute root in static html files;
  namely CommandGuide tools hard codes a website destination
  for cross references and some html cross references assume
  website root paths

*** IMPROVEMENTS

- bumped Doxygen from 1.4.x -> 1.6.3
- splits llvm/clang docs into 'main' and 'api' (doxygen) build trees
- provide consistent, reliable doc builds for both main+api docs
- support buid vs. install vs. website intentions
- support objdir builds
- document targets with 'make help'
- correct clean and uninstall operations
- use recursive dir delete only where absolutely necessary
- added call function fn.RMRF which safeguards against botched 'rm -rf';
  if any target (or any variable is evaluated) which attempts
  to remove any dirs which match a hard-coded 'safelist', a verbose
  error will be printed and make will error-stop.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@103213 91177308-0d34-0410-b5e6-96231b3b80d8

docs/CommandGuide/llvmgcc.pod

@@ -1,76 +0,0 @@
-=pod
-
-=head1 NAME
-
-llvm-gcc - LLVM C front-end
-
-=head1 SYNOPSIS
-
-B<llvm-gcc> [I<options>] I<filename>
-
-=head1 DESCRIPTION
-
-The B<llvm-gcc> command is the LLVM C front end.  It is a modified
-version of gcc that compiles C/ObjC programs into native objects, LLVM
-bitcode or LLVM assembly language, depending upon the options.
-
-By default, B<llvm-gcc> compiles to native objects just like GCC does. If the
-B<-emit-llvm> and B<-c> options are given then it will generate LLVM bitcode files
-instead. If B<-emit-llvm> and B<-S> are given, then it will generate LLVM
-assembly.
-
-Being derived from the GNU Compiler Collection, B<llvm-gcc> has many
-of gcc's features and accepts most of gcc's options.  It handles a
-number of gcc's extensions to the C programming language.  See the gcc
-documentation for details.
-
-=head1 OPTIONS
-
-=over
-
-=item B<--help>
-
-Print a summary of command line options.
-
-=item B<-o> I<filename>
-
-Specify the output file to be I<filename>.
-
-=item B<-I> I<directory>
-
-Add a directory to the header file search path.  This option can be
-repeated.
-
-=item B<-L> I<directory>
-
-Add I<directory> to the library search path.  This option can be
-repeated.
-
-=item B<-l>I<name>
-
-Link in the library libI<name>.[bc | a | so].  This library should
-be a bitcode library.
-
-=item B<-emit-llvm>
-
-Make the output be LLVM bitcode (with B<-c>) or assembly (with B<-s>) instead
-of native object (or assembly).  If B<-emit-llvm> is given without either B<-c>
-or B<-S> it has no effect.
-
-=back
-
-=head1 EXIT STATUS
-
-If B<llvm-gcc> succeeds, it will exit with 0.  Otherwise, if an error
-occurs, it will exit with a non-zero value.
-
-=head1 SEE ALSO
-
-L<llvm-g++|llvmgxx>
-
-=head1 AUTHORS
-
-Maintained by the LLVM Team (L<http://llvm.org>).
-
-=cut
-