gcc: or1k: use 20170218 tag instead of branch

As pointed out by Joel Stanley:
https://patchwork.ozlabs.org/patch/863011/

Github now longer provides the exact same tarball for the or1k musl-5.4.0
tarball, breaking the build.  Even more, musl-5.4.0 is the name of a git
branch, not a tag.

Fix both problems by changing to the or1k-musl-5.4.0-20170218 tag, which
points to the exact same git commit.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Tested-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/gcc/Config.in.host

@@ -81,7 +81,7 @@ config BR2_GCC_VERSION
 	default "6.4.0"     if BR2_GCC_VERSION_6_X
 	default "7.3.0"     if BR2_GCC_VERSION_7_X
 	default "arc-2017.09-release" if BR2_GCC_VERSION_ARC
-	default "musl-5.4.0" if BR2_GCC_VERSION_OR1K
+	default "or1k-musl-5.4.0-20170218" if BR2_GCC_VERSION_OR1K
 
 config BR2_EXTRA_GCC_CONFIG_OPTIONS
 	string "Additional gcc options"

package/gcc/gcc.hash

@@ -10,4 +10,4 @@ sha512  ad41a7e4584e40e92cdf860bc0288500fbaf5dfb7e8c3fcabe9eba809c87bcfa85b46c19
 # Locally calculated (fetched from Github)
 sha512  c30addd3c4dc66b90749a0f99b257c8a8e7966d27f286057b6b66f4a70ca22a1ee50d92882c4db13307d769a6fb28e1e2a2bab749a692cf3f89ef0c38f145efa  gcc-arc-2017.09-release.tar.gz
 # Locally calculated (fetched from Github)
-sha512  841101f7de45f327bf2e92f3efc73ca88a021e4b9b541458ce80a16e55882bd8606a8492d75c57c589ee2c10d42ae2865b67690155d7289a541df1d68096402f  gcc-musl-5.4.0.tar.gz
+sha512  2de7cf47333a4092b02d3bb98f4206f14966f1d139a724d09cf3b22f8a43ae0c704f33e6477d6367a03c29b265480dc900169e9d417006c5d46f0ae446b8c6f1  gcc-or1k-musl-5.4.0-20170218.tar.gz