STYLE: update some build comments regarding min gcc for clang

BUILD.md

@@ -297,8 +297,12 @@ install the 32-bit development libraries by default.
 The minimum version of clang required is 3.3.
 
 *Attention*: If you are building a newer version of clang, you may need to
-update your CMake beforehand.
+update your CMake beforehand since GNU *configure* can only be used prior
-GNU *configure* can only be used prior to clang version 3.9.
+to clang version 3.9.
+
+If your system gcc is particularly old
+(see [minimum gcc requirements for clang](#min-gcc))
+you may have additional hurdles to using the newest versions of clang.
 
 
 | Name                  | Location
@@ -365,6 +369,10 @@ The minimum gcc/g++ requirements for building various components.
     4.7         llvm-3.5.2
     4.4         llvm-3.4.2
 
+If your system gcc/g++ is too old to build the desired llvm/clang
+version, you may need to build a lower llvm/clang version and then use
+that clang compiler for building the newer llvm/clang version.
+
 
 <!-- gcc-related -->
 [page gcc]:       http://gcc.gnu.org/releases.html
@@ -457,6 +465,7 @@ The minimum gcc/g++ requirements for building various components.
 [link AddOns]: https://develop.openfoam.com/Community/OpenFOAM-addOns
 [link community-projects]: http://www.openfoam.com/community/projects.php
 
+---
 
 <!-- Standard Footer -->
 ## Additional OpenFOAM Links

README.md

@@ -72,6 +72,7 @@ More details can be found the ThirdParty BUILD.md information.
 [link AddOns]: https://develop.openfoam.com/Community/OpenFOAM-addOns
 [link community-projects]: http://www.openfoam.com/community/projects.php
 
+---
 
 <!-- Standard Footer -->
 ## Additional OpenFOAM Links

SOURCES.txt

@@ -49,7 +49,7 @@ openmpi-1.10.0      *update*
 scotch_6.0.3
 
 
-OpenFOAM-v2.4+
+OpenFOAM-v2.4
 ---------------
 CGAL-4.6            *update*
 ParaView-4.1.0