Fortran: improve runtime error message with ALLOCATE and ERRMSG= [PR91300]
ALLOCATE: generate different STAT,ERRMSG results for failures from
allocation of already allocated objects or insufficient virtual memory.
gcc/fortran/ChangeLog:
PR fortran/91300
* libgfortran.h: Define new error code LIBERROR_NO_MEMORY.
* trans-stmt.cc (gfc_trans_allocate): Generate code for setting
ERRMSG depending on result of STAT result of ALLOCATE.
* trans.cc (gfc_allocate_using_malloc): Use STAT value of
LIBERROR_NO_MEMORY in case of failed malloc.
gcc/testsuite/ChangeLog:
PR fortran/91300
* gfortran.dg/allocate_alloc_opt_15.f90: New test.