Disable link-time optimizations for now because it breaks Ubuntu 15

builds.  :-(

Author: dspeterson

SConstruct

@@ -166,15 +166,18 @@ def set_debug_options():
 
 
 def set_release_options():
+    # Enabling link-time optimizations breaks the build on Ubuntu 15, so for
+    # now we avoid enabling them.  What a chore it is to get stuff to build on
+    # multiple platforms.  :-(
+
     env.AppendUnique(CCFLAGS=['-O2', '-DNDEBUG', '-Wno-unused',
-                              '-Wno-unused-parameter', '-flto',
-                              '-fvisibility=hidden'])
+                              '-Wno-unused-parameter', '-fvisibility=hidden'])
 
     # Unfortunately this is needed to prevent spurious build errors on Ubuntu
     # 14.  :-(
     env.AppendUnique(CPPFLAGS=['-U_FORTIFY_SOURCE'])
 
-    env.AppendUnique(LINKFLAGS=['-flto', '-rdynamic'])
+    env.AppendUnique(LINKFLAGS=['-rdynamic'])
 
 
 # Append 'mode' specific environment variables.