mesa: automake: ensure that git_sha1.h.tmp has the right attributes
mesa: automake: ensure that git_sha1.h.tmp has the right attributes

... when copied from git_sha1.h.

As the latter file can we lacking the write attribute, one should set it
explicitly. Otherwise we'll get a warning/failure at cleanup stage.

Cc: <59f39c0db42d4479a46b02d4d2bc11120e37bb44@lists.freedesktop.org>
Signed-off-by: Emil Velikov <f20878473f414da183da19ee25c8722cc1d711e4@collabora.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler