python-3.7.6: Add LD_LIBRARY_PATH

We are going to install Tensorflow into this package.

Tensorflow loads implementation libraries at runtime which need to be
found. Add LD_LIBRARY_PATH to avoid runtime errors like

    Traceback (most recent call last):
      File "/dev/shm/python-3.7.6-0/lib/python3.7/site-packages/tensorflow-2.1.0-py3.7-linux-x86_64.egg/tensorflow_core/python/pywrap_tensorflow.py", line 58, in <module>
        from tensorflow.python.pywrap_tensorflow_internal import *
      File "/dev/shm/python-3.7.6-0/lib/python3.7/site-packages/tensorflow-2.1.0-py3.7-linux-x86_64.egg/tensorflow_core/python/pywrap_tensorflow_internal.py", line 28, in <module>
        _pywrap_tensorflow_internal = swig_import_helper()
      File "/dev/shm/python-3.7.6-0/lib/python3.7/site-packages/tensorflow-2.1.0-py3.7-linux-x86_64.egg/tensorflow_core/python/pywrap_tensorflow_internal.py", line 24, in swig_import_helper
        _mod = imp.load_module('_pywrap_tensorflow_internal', fp, pathname, description)
      File "/dev/shm/python-3.7.6-0/lib/python3.7/imp.py", line 242, in load_module
        return load_dynamic(name, filename, file)
      File "/dev/shm/python-3.7.6-0/lib/python3.7/imp.py", line 342, in load_dynamic
        return _load(spec)
    ImportError: libnccl.so.2: cannot open shared object file: No such file or directory

python-3.7.6-0.build.sh

@@ -27,6 +27,7 @@ mkdir -p $PREFIX
 cat >$PREFIX/profile <<-EOF
 	. $CUDADIR/profile
 	PATH=$PREFIX/bin:\$PATH
+	export LD_LIBRARY_PATH=$PREFIX/lib\${LD_LIBRARY_PATH:+:}\$LD_LIBRARY_PATH
 	PKG_CONFIG_PATH=$PREFIX/lib/pkgconfig\${PKG_CONFIG_PATH:+:\$PKG_CONFIG_PATH}
 	export PKG_CONFIG_PATH
 	if [ -d $PREFIX/.compatlibs ]; then export LD_LIBRARY_PATH=$PREFIX/.compatlibs\${LD_LIBRARY_PATH:+:\$LD_LIBRARY_PATH} ; fi