In https://sourceware.org/ml/libc-alpha/2014-12/msg00300.html, we give a
"called from here" note without actually having a location, which looks
strange. I haven't been able to generate such a testcase. If this happens,
try to at least point to the current function being called. If that location is
also unknown, skip the extra note.

gcc/ChangeLog:

2015-09-21  Manuel López-Ibáñez  <manu@gcc.gnu.org>

    * tree-inline.c (expand_call_inline): Use inform for extra note.
    Do not give a note with UNKNOWN_LOCATION.
    Replace input_location with gimple_location (stmt).
    Use true instead of TRUE.

gcc/testsuite/ChangeLog:

2015-09-21  Manuel López-Ibáñez  <manu@gcc.gnu.org>

    * gcc.target/i386/inline_error.c (int bar): Use dg-message for note.
    * gcc.target/i386/pr57756.c (static __inline int caller): Likewise.
    * gcc.target/i386/pr59789.c (f1): Likewise.
    * gcc.target/i386/intrinsics_5.c (__m128i foo): Likewise.
    * gcc.target/i386/intrinsics_6.c: Likewise.
    * gcc.dg/winline-5.c (int t): Likewise.
    * gcc.dg/winline-9.c (t): Likewise.
    * gcc.dg/always_inline2.c (q): Likewise.
    * gcc.dg/winline-2.c (inline int t): Likewise.
    * gcc.dg/winline-6.c: Likewise.
    * gcc.dg/winline-10.c (void g): Likewise.
    * gcc.dg/pr49243.c (void parse): Likewise.
    * gcc.dg/always_inline3.c (q2): Likewise.
    * gcc.dg/winline-3.c: Likewise.
    * gcc.dg/winline-7.c (inline void *t): Likewise.