pkgsrc:
 - Not to set USE_CROSSBASE, syncing to avr-{binutils,gcc}
 - Remove unnecessary BUILD_DEPENDS, see .include buildlink3.mk

Upstream:
(from NEWS file)
*** Changes in avr-libc-1.8.0:

* Bugs fixed:

  [#17815] Configure does not honor --mandir option
  [#23234] Alternate interrupt macro
  [#24861] Interrupt documentation contains extra include
  [#32103] Support for Target-Triplets
  [#32419] Incorrect EEPROM size in header for ATxmega192A3
  [#32650] Missing include in util/delay.h
  [#32675] power_all_enable/disable does not affect timer1 on ATmega164P
  [#32698] power.h has additional endif that will break the build
  [#32773] stdiodemo source code is broken
  [#32988] Internal compiler error: build_unary_op
  [#33130] twitest.c source code is broken
  [#33230] Sleep modes have incorrect names for ATtiny261/461/861
  [#33238] Wrong _VECTORS_SIZE for mega8U2 et al
  [#33858] in avr/power.h, clock_prescale_set() not defined for mega328
  [#33920] ICR1 incorrectly defined for tiny167
  [#34047] missing math.h include in delay.h
  [#34514] misspelled in math.h
  [#35020] stdint.h: signed types need explicit "signed"
  [#35093] strlcat_P fails for some destinations
  [no-id]  New names for CLKSTA/CLKSEL0/1 for AT90USB82/162
  system when power_all_disable() is used
  [no-id]  util/delay.h would not compile with -ffreestanding

* New devices supported:

* Contributed Patches:

  [#7531] Bad name of bit in TCCR0A : WGM0 instead of CTC0 for ATtinyX61
  [#7362] iom16a.h: USART vectors inconsistently named for ATmega16A
  [#7226] ATMEGA8U2 Patches

* Other changes:

  - The old prog_* typedefs are now deprecated, and are only included
  if requested by the user.  This request is expressed by declaring
  the macro __PROG_TYPES_COMPAT__, either by a #define directive
  before including <avr/pgmspace.h>, or by a -D compiler option.

  - Optimized strlen_P, thanks to Jan Waclawek. Rename strlen_P to be
  __strlen_P and add new strlen_P inline function in header file that
  checks if value is a constant and known at compile time. If not,
  then the new inline function calls __strlen_P as normal.