Fixes for a small number of compiler warnings

Fixes for a small number of compiler warnings

The ehdr_start_save variable does not need to be initialized.  However,
not initializing it will trigger a compiler warning when using older
versions of GCC.  Self-assignment unfortunately doesn't work for Clang
as Clang has a warning similar to -Winit-self as part of -Wall.

	* emultempl/elf32.em (gld*_before_allocation): Zero-initialize
	the ehdr_start_save variable.