linux: Make profil_counter a compat_symbol (BZ#17726)

As indicated by Joseph's comment on BZ#17726, this symbol is most
likely a historical ABI accident.  This patch make it on both arm
and sparc ABIs a compat_symbol.

Checked against a build arm-linux-gnueabihf, sparcv9-linux-gnu, adn
sparc64-linux-gnu to see if the symbol is still present.

	* gmon/Versions (libc) [GLIBC_2.31]: New entry.
	* sysdeps/unix/sysv/linux/arm/profil-counter.h (profil_counter):
	Make a compat_symbol.
	* sysdeps/unix/sysv/linux/sparc/profil-counter.h
	(__profil_counter_global): Likewise.