gnu: llvm-rtti: Remove it.

This reverts commit f8cba3ff4f.

It sounds from the comment that this should be removed now, as it's been a
while since this change was made.

* gnu/packages/llvm.scm (llvm-without-rtti): Remove it.
* gnu/packages/gl.scm (mesa)[inputs]: Switch to using llvm rather than
llvm-without-rtti.

gnu/packages/gl.scm

@@ -255,8 +255,7 @@ also known as DXTn or DXTC) for Mesa.")
         ("libxvmc" ,libxvmc)
         ,@(match (%current-system)
             ((or "x86_64-linux" "i686-linux")
-             ;; FIXME: Change to 'llvm' in the next rebuild cycle.
-             `(("llvm" ,llvm-without-rtti)))
+             `(("llvm" ,llvm)))
             (_
              `()))
         ("makedepend" ,makedepend)

gnu/packages/llvm.scm

@@ -95,26 +95,6 @@ languages is in development.  The compiler infrastructure includes mirror sets
 of programming tools as well as libraries with equivalent functionality.")
     (license license:ncsa)))
 
-;; FIXME: This package is here to prevent many rebuilds on x86_64 and i686
-;; from commit fc9dbf41311d99d0fd8befc789ea7c0e35911890.  Update users of
-;; this in the next rebuild cycle.
-(define-public llvm-without-rtti
-  (package
-    (inherit llvm)
-    (arguments
-     `(#:configure-flags '("-DCMAKE_SKIP_BUILD_RPATH=FALSE"
-                           "-DCMAKE_BUILD_WITH_INSTALL_RPATH=FALSE"
-                           "-DBUILD_SHARED_LIBS:BOOL=TRUE"
-                           "-DLLVM_ENABLE_FFI:BOOL=TRUE"
-                           "-DLLVM_INSTALL_UTILS=ON")
-       #:build-type "Release"
-       #:phases (modify-phases %standard-phases
-                  (add-before 'build 'shared-lib-workaround
-                    (lambda _
-                      (setenv "LD_LIBRARY_PATH"
-                              (string-append (getcwd) "/lib"))
-                      #t)))))))
-
 (define* (clang-runtime-from-llvm llvm hash
                                   #:optional (patches '()))
   (package