gnu: Add GCC 4.9.0.

* gnu/packages/gcc.scm (gcc-4.9): New variable.
* gnu/packages/base.scm (gcc-toolchain-4.9): New variable.

gnu/packages/base.scm

@@ -1175,4 +1175,7 @@ (define (gcc-toolchain gcc)
 (define-public gcc-toolchain-4.8
   (gcc-toolchain gcc-final))
 
+(define-public gcc-toolchain-4.9
+  (gcc-toolchain gcc-4.9))
+
 ;;; base.scm ends here

gnu/packages/gcc.scm

@@ -227,6 +227,17 @@ (define-public gcc-4.8
               (base32
                "1j6dwgby4g3p3lz7zkss32ghr45zpdidrg8xvazvn91lqxv25p09"))))))
 
+(define-public gcc-4.9
+  (package (inherit gcc-4.7)
+    (version "4.9.0")
+    (source (origin
+             (method url-fetch)
+             (uri (string-append "mirror://gnu/gcc/gcc-"
+                                 version "/gcc-" version ".tar.bz2"))
+             (sha256
+              (base32
+               "0mqjxpw2klskls00lwx1k24pnyzm3whqxg3hk74c3sddgfllgc5r"))))))
+
 (define (custom-gcc gcc name languages)
   "Return a custom version of GCC that supports LANGUAGES."
   (package (inherit gcc)