Add a NativeCall pseudo-opcode to VIXL

We'll need the ability to call native functions (i.e. written in C++)
out of the simulated-ARM translation cache. VIXL already has support for
pseudo-opcodes that the simulator understands and treats specially (it's
a trap instruction with payload in some unallocated bits), so I added a
new one that will read a function address out of an inter-procedural
scratch register and arguments out of the usual argument registers, call
the native function, smash simulated caller-saved registers, and put the
return value in the simulated return value register.

Differential Revision: D916164
Rewrite findBody and findForInsertBody as functions taking lambdas.

The way we use these macros is exactly what lambdas are for, so
give it a try.

Differential Revision: D916121
Rename string_data-inl.h to string-data-inl.h

Differential Revision: D917064
Fix TLS CURLOPT when SSL_OP_NO_TLSv1_1 not defined

This was busted in two ways:
1. SSL_OP_NO_TLSv1_1 wasn't guarded by an ifdef in one location
2. SSL_OP_NO_TLSv1_1 was used instead of SSL_OP_NO_TLSv1_2
in one location.

Differential Revision: D917255