Build fixes

[mcspr]

As mentioned in the https://github.com/earlephilhower/newlib-xtensa/issues/19#issuecomment-906051683 Solves the issue with building on current Debian 11 by

• regenerating libelf ./configure, otherwise it would incorrectly detect the current compiler command and fail the checking whether the C compiler works... step
• adding binutils patch ignoring _FORTIFY_SOURCE (and per https://sourceware.org/git/?p=binutils-gdb.git;a=history;f=gdb/gdbsupport/common-defs.h, there are no further changes)