[Merge][Bugfix] r7422 from branches/release-cmake-2.2: Prevent definition of...

[Merge][Bugfix] r7422 from branches/release-cmake-2.2: Prevent definition of HAVE_BOOST without value due to race conditions i
n some autoconf versions.

For some autoconf versions there was a race condition between ax_boost_base.m4 a
nd dune_boost_base.m4 resulting in HAVE_BOOST being defined with no value (inste
ad of ENABLE_BOOST). For others there were even two definitions of it (one with 
and one without value). 

This patch renames the symbol being defined in dune_boost_base.m4 to HAVE_DUNE_B
OOST and defines a value for it if boost is found.


[[Imported from SVN: r7424]]

m4/dune_boost_base.m4

@@ -17,7 +17,7 @@
 #
 #   And sets:
 #
-#     HAVE_BOOST
+#     HAVE_DUNE_BOOST
 #        ENABLE_BOOST or undefined. Whether boost was found. The correct way to
 #        to check this is "#if HAVE_BOOST": This way boost features will be disabled
 #        unless ${BOOST_CPPFLAGS} was given when compiling
@@ -25,7 +25,7 @@
 AC_DEFUN([DUNE_BOOST_BASE],
 [
 AX_BOOST_BASE([$1],[
-  AC_DEFINE(HAVE_BOOST, [ENABLE_BOOST],[Define to ENABLE_BOOST if the Boost library is available])
+  AC_DEFINE(HAVE_DUNE_BOOST, [ENABLE_BOOST],[Define to ENABLE_BOOST if the Boost library is available])
   BOOST_CPPFLAGS="$BOOST_CPPFLAGS -DENABLE_BOOST"
   AC_SUBST(BOOST_CPPFLAGS)
   # execute ACTION-IF-FOUND (if present):