Mitigation for PR target/88469 on arm-based systems bootstrapping with gcc-6/7/8

Mitigation for PR target/88469 on arm-based systems bootstrapping with gcc-6/7/8

This patch, for gcc 8/9 is a mitigation patch for PR target/88469
where gcc-6/7/8 miscompile a structure whose alignment is dominated by
a 64-bit bitfield member.  Since the PCS rules for such a type must
ignore any overalignment of the base type we cannot address this by
simply adding a larger alignment to the class.  We can, however, force
the alignment of the bit-field itself and GCC will handle that as
desired.

	PR target/88469
	* profile-count.h (profile_count): On ARM systems using GCC 6/7/8
	force the alignment of m_val.

From-SVN: r268240