Auto-sync with upstream branch master
    
    Upstream commit: 596f70134a8f11967c65c1d55a94a3a2718c731d
    
    - Silence -O3 -Wall warning in malloc/hooks.c with GCC 7 (swbz#22052)
    - locale: No warning for non-symbolic character (swbz#22295)
    - locale: Allow "" int_curr_Symbol (swbz#22294)
    - locale: Fix localedef exit code (swbz#22292)
    - nptl: Preserve error in setxid thread broadcast in coredumps (swbz#22153)
    - powerpc: Avoid putting floating point values in memory (swbz#22189)
    - powerpc: Fix the carry bit on mpn_[add|sub]_n on POWER7 (swbz#22142)
    - Support profiling PIE (swbz#22284)