build: Disallow dynamic linking against c++ library

Ever since statically linking Qt, we've been linking the C++ library
statically too (-static-libstdc++). Take this into
account in the symbol checker.

contrib/devtools/symbol-check.py

@@ -4,8 +4,8 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 '''
 A script to check that the (Linux) executables produced by gitian only contain
-allowed gcc, glibc and libstdc++ version symbols.  This makes sure they are
-still compatible with the minimum supported Linux distribution versions.
+allowed gcc and glibc version symbols. This makes sure they are still compatible
+with the minimum supported Linux distribution versions.
 
 Example usage:
 
@@ -20,25 +20,20 @@ import os
 #
 # - g++ version 4.4.5 (https://packages.debian.org/search?suite=default&section=all&arch=any&searchon=names&keywords=g%2B%2B)
 # - libc version 2.11.3 (https://packages.debian.org/search?suite=default&section=all&arch=any&searchon=names&keywords=libc6)
-# - libstdc++ version 4.4.5 (https://packages.debian.org/search?suite=default&section=all&arch=any&searchon=names&keywords=libstdc%2B%2B6)
 #
 # Ubuntu 10.04.4 (Lucid Lynx) has:
 #
 # - g++ version 4.4.3 (http://packages.ubuntu.com/search?keywords=g%2B%2B&searchon=names&suite=lucid&section=all)
 # - libc version 2.11.1 (http://packages.ubuntu.com/search?keywords=libc6&searchon=names&suite=lucid&section=all)
-# - libstdc++ version 4.4.3 (http://packages.ubuntu.com/search?suite=lucid&section=all&arch=any&keywords=libstdc%2B%2B&searchon=names)
 #
 # Taking the minimum of these as our target.
 #
 # According to GNU ABI document (http://gcc.gnu.org/onlinedocs/libstdc++/manual/abi.html) this corresponds to:
 #   GCC 4.4.0: GCC_4.4.0
-#   GCC 4.4.2: GLIBCXX_3.4.13, CXXABI_1.3.3
 #   (glibc)    GLIBC_2_11
 #
 MAX_VERSIONS = {
 'GCC':       (4,4,0),
-'CXXABI':    (1,3,3),
-'GLIBCXX':   (3,4,13),
 'GLIBC':     (2,11),
 'LIBATOMIC': (1,0)
 }