[gdb] Fix more typos in comments

[gdb] Fix more typos in comments

Fix typos in comments.  NFC.

Tested on x86_64-linux.

gdb/ChangeLog:

2019-10-18  Tom de Vries  <tdevries@suse.de>

	* aarch64-tdep.c: Fix typos in comments.
	* ada-lang.c: Same.
	* ada-tasks.c: Same.
	* alpha-tdep.c: Same.
	* alpha-tdep.h: Same.
	* amd64-nat.c: Same.
	* amd64-windows-tdep.c: Same.
	* arc-tdep.c: Same.
	* arc-tdep.h: Same.
	* arch-utils.c: Same.
	* arm-nbsd-tdep.c: Same.
	* arm-tdep.c: Same.
	* ax-gdb.c: Same.
	* blockframe.c: Same.
	* btrace.c: Same.
	* c-varobj.c: Same.
	* coff-pe-read.c: Same.
	* coffread.c: Same.
	* cris-tdep.c: Same.
	* darwin-nat.c: Same.
	* dbxread.c: Same.
	* dcache.c: Same.
	* disasm.c: Same.
	* dtrace-probe.c: Same.
	* dwarf-index-write.c: Same.
	* dwarf2-frame-tailcall.c: Same.
	* dwarf2-frame.c: Same.
	* dwarf2read.c: Same.
	* eval.c: Same.
	* exceptions.c: Same.
	* fbsd-tdep.c: Same.
	* findvar.c: Same.
	* frame.c: Same.
	* frv-tdep.c: Same.
	* gnu-v3-abi.c: Same.
	* go32-nat.c: Same.
	* h8300-tdep.c: Same.
	* hppa-tdep.c: Same.
	* i386-linux-tdep.c: Same.
	* i386-tdep.c: Same.
	* ia64-libunwind-tdep.c: Same.
	* ia64-tdep.c: Same.
	* infcmd.c: Same.
	* infrun.c: Same.
	* linespec.c: Same.
	* linux-nat.c: Same.
	* linux-thread-db.c: Same.
	* machoread.c: Same.
	* mdebugread.c: Same.
	* mep-tdep.c: Same.
	* mn10300-tdep.c: Same.
	* namespace.c: Same.
	* objfiles.c: Same.
	* opencl-lang.c: Same.
	* or1k-tdep.c: Same.
	* osabi.c: Same.
	* ppc-linux-nat.c: Same.
	* ppc-linux-tdep.c: Same.
	* ppc-sysv-tdep.c: Same.
	* printcmd.c: Same.
	* procfs.c: Same.
	* record-btrace.c: Same.
	* record-full.c: Same.
	* remote-fileio.c: Same.
	* remote.c: Same.
	* rs6000-tdep.c: Same.
	* s12z-tdep.c: Same.
	* score-tdep.c: Same.
	* ser-base.c: Same.
	* ser-go32.c: Same.
	* skip.c: Same.
	* sol-thread.c: Same.
	* solib-svr4.c: Same.
	* solib.c: Same.
	* source.c: Same.
	* sparc-nat.c: Same.
	* sparc-sol2-tdep.c: Same.
	* sparc-tdep.c: Same.
	* sparc64-tdep.c: Same.
	* stabsread.c: Same.
	* stack.c: Same.
	* symfile.c: Same.
	* symtab.c: Same.
	* target-descriptions.c: Same.
	* target-float.c: Same.
	* thread.c: Same.
	* utils.c: Same.
	* valops.c: Same.
	* valprint.c: Same.
	* value.c: Same.
	* varobj.c: Same.
	* windows-nat.c: Same.
	* xcoffread.c: Same.
	* xstormy16-tdep.c: Same.
	* xtensa-tdep.c: Same.

Change-Id: I5175f1b107bfa4e1cdd4a3361ccb4739e53c75c4