Allow binaries without any shared libraries to be used for runnable_binary

[rueteh]

When using the runnable_binary macro with a binary e.g. diff that does not involve any shared libraries, the following error is produced:

line 46: SHARED_LIBS_ARRAY[@]: unbound variable

As find . -name "*${SHARED_LIB_SUFFIX}" -print0 does not return any results (thus SHARED_LIBS_ARRAY) , along with set -uo earlier in the script, this assumes that there will always be some shared library files.

This PR bring the set +u command earlier to allow the variable to be empty if there are only static libraries involved.

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