gdb: update corner case when canonicalizing riscv syscall names

The script syscalls/riscv-canonicalize-syscall-gen.py has been recently
introduced to help support record-full in riscv systems.  However, it
was developed before commit 432eca4,
which made the GDB enum more consistent, which forced the python script
to have a corner case for the "gdb_old_mmap" case.

Since the aforementioned commit has already been merged, we need to
update the special case for the mmap syscall. A special case is still
needed because the script would expect that the glibc sources call the
syscall "old_mmap", or that gdb call it "gdb_sys_mmap", neither of which
happens unfortunately.

This commit doesn't change the .c file because it was already fixed by a
different commit, 65ab41b, which was
pushed as obvious to fix the build issues.

Approved-By: Tom Tromey <[email protected]>

Author: Guinevere Larsen

gdb/syscalls/riscv-canonicalize-syscall-gen.py

@@ -111,7 +111,7 @@ def _get_canon_syscalls_lines(
                         canon_syscalls[syscall_num] = value
                     # this is a place for corner cases
                     elif syscall_name == "mmap":
-                        gdb_old_syscall_name = "gdb_old_mmap"
+                        gdb_old_syscall_name = "gdb_sys_old_mmap"
                         value = (
                             f"    case {syscall_num}: return {gdb_old_syscall_name};\n"
                         )