MIPS: Use R_MICROMIPS_JALR rather than R_MIPS_JALR in microMIPS code

In a microMIPS compilation of `.init' code use the R_MICROMIPS_JALR
relocation intended for PIC call relaxation in microMIPS code rather
than the corresponding R_MIPS_JALR relocation meant for regular MIPS
code only.

	* sysdeps/mips/mips32/crti.S (JALR_RELOC): New macro.
	(_init): Use it in place of hardcoded R_MIPS_JALR.
	* sysdeps/mips/mips64/n32/crti.S (JALR_RELOC): New macro.
	(_init): Use it in place of hardcoded R_MIPS_JALR.
	* sysdeps/mips/mips64/n64/crti.S (JALR_RELOC): New macro.
	(_init): Use it in place of hardcoded R_MIPS_JALR.