gdb: Remove whitespace in 'std::vector <...>'

gdb: Remove whitespace in 'std::vector <...>'

In the following 3 commits:

    commit df07e2c772dab40d268dc44c78bb087c4b75b3c6
    Date:   Wed Sep 25 16:10:50 2019 +0100

        gdb: Remove a use of VEC from dwarf2read.{c,h}

    commit 554ac434b02465f1fc925b0ae3393fb841e0d59c
    Date:   Thu Sep 19 13:17:59 2019 -0400

        gdb: Change a VEC to std::vector in btrace.{c,h}

    commit 46f29a9a260da1a03176682aff63bad03d8f2e8b
    Date:   Mon Sep 16 09:12:27 2019 -0400

        gdb: Remove a VEC from gdbsupport/btrace-common.h

I incorrectly wrote 'std::vector <...>' instead of 'std::vector<...>',
this commit fixes this mistake.  There should be no user visible
changes after this commit.

gdb/ChangeLog:

	* btrace.c (btrace_add_pc): Remove whitespace before the template
	parameter in 'std::vector <...>'.
	(parse_xml_btrace_block): Likewise.
	(btrace_maint_decode_pt): Likewise.
	(btrace_maint_update_packets): Likewise.
	(btrace_maint_print_packets): Likewise.
	* btrace.h (struct btrace_maint_info): Likewise.
	* dwarf2read.c (struct type_unit_group): Likewise.
	(build_type_psymtabs_reader): Likewise.
	* gdbsupport/btrace-common.c (btrace_data_append): Likewise.
	* gdbsupport/btrace-common.h (struct btrace_data_bts): Likewise.
	* nat/linux-btrace.c (perf_event_read_bts): Likewise.