gdb/fortran: Fix quad floating-point type for Intel compilers.

gdb/fortran: Fix quad floating-point type for Intel compilers.

Intel Fortran compilers emit the following DWARF for gdb.fortran/complex.f90:

0x00000071:   DW_TAG_base_type
                DW_AT_name	("COMPLEX*32")
                DW_AT_encoding	(DW_ATE_complex_float)
                DW_AT_byte_size	(0x20)

0x00000078:   DW_TAG_base_type
                DW_AT_name	("REAL*16")
                DW_AT_encoding	(DW_ATE_float)
                DW_AT_byte_size	(0x10)

This results in GDB not reading the right values, as it wrongly assumes the
default floatformat "floatformat_i387_ext" instead of
"floatformat_ia64_quad_little".

gdb/ChangeLog:
2021-03-15  Felix Willgerodt  <felix.willgerodt@intel.com>

	* i386-tdep.c (i386_floatformat_for_type): Add COMPLEX*32 and REAL*16.