gdb: Fix std::{min, max}-related build breakage on 32-bit hosts

gdb: Fix std::{min, max}-related build breakage on 32-bit hosts

Building on a 32-bit host fails currently with errors like:

  .../src/gdb/exec.c: In function ‘target_xfer_status section_table_read_available_memory(gdb_byte*, ULONGEST, ULONGEST, ULONGEST*)’:
  .../src/gdb/exec.c:801:54: error: no matching function for call to ‘min(ULONGEST, long unsigned int)’
      end = std::min (offset + len, r->start + r->length);
							^
  In file included from /usr/include/c++/5.3.1/algorithm:61:0,
		   from .../src/gdb/exec.c:46:
  /usr/include/c++/5.3.1/bits/stl_algobase.h:195:5: note: candidate: template<class _Tp> const _Tp& std::min(const _Tp&, const _Tp&)
       min(const _Tp& __a, const _Tp& __b)
       ^
  /usr/include/c++/5.3.1/bits/stl_algobase.h:195:5: note:   template argument deduction/substitution failed:
  .../src/gdb/exec.c:801:54: note:   deduced conflicting types for parameter ‘const _Tp’ (‘long long unsigned int’ and ‘long unsigned int’)
      end = std::min (offset + len, r->start + r->length);
							^
  In file included from /usr/include/c++/5.3.1/algorithm:61:0,
		   from .../src/gdb/exec.c:46:
  /usr/include/c++/5.3.1/bits/stl_algobase.h:243:5: note: candidate: template<class _Tp, class _Compare> const _Tp& std::min(const _Tp&, const _Tp&, _Compare)
       min(const _Tp& __a, const _Tp& __b, _Compare __comp)
       ^

The problem is that the std::min/std::max function templates use the
same type for both parameters.  When the argument types are different,
the compiler can't automatically deduce which template specialization
to pick from the arguments' types.

Fix that by specifying the specialization we want explicitly.

gdb/ChangeLog:
2016-09-18  Pedro Alves  <palves@redhat.com>

	* breakpoint.c (hardware_watchpoint_inserted_in_range): Explicitly
	specify the std:min/std::max specialization.
	* exec.c (section_table_read_available_memory): Likewise.
	* remote.c (remote_read_qxfer): Likewise.
	* target.c (simple_verify_memory): Likewise.