[mips] Correct section alignments and EntrySizes for .bss, .text, .data, .reginfo, .MIPS.options, and .MIPS.abiflags

Summary:
.bss, .text, and .data are at least 16-byte aligned.
.reginfo is 4-byte aligned and has a 24-byte EntrySize.
.MIPS.abiflags has an 24-byte EntrySize.
.MIPS.options is 8-byte aligned and has 1-byte EntrySize.

Using a 1-byte EntrySize for .MIPS.options seems strange because the
records are neither 1-byte long nor fixed-length but this matches the value
that GAS emits.

Differential Revision: http://reviews.llvm.org/D4487