network/lurc: Fixed build with gcc-5.2.0.

Signed-off-by: David Spencer <baildon.research@googlemail.com>

network/lurc/lurc.SlackBuild

@@ -69,9 +69,10 @@ find -L . \
  -o -perm 440 -o -perm 400 \) -exec chmod 644 {} \;
 
 cmake \
-  -DCMAKE_C_FLAGS:STRING="$SLKCFLAGS" \
-  -DCMAKE_CXX_FLAGS:STRING="$SLKCFLAGS" \
+  -DCMAKE_C_FLAGS_RELEASE:STRING="$SLKCFLAGS -fgnu89-inline" \
+  -DCMAKE_CXX_FLAGS_RELEASE:STRING="$SLKCFLAGS" \
   -DCMAKE_INSTALL_PREFIX=/usr \
+  -DCMAKE_BUILD_TYPE=Release \
   .
 
 make