LoongArch: Use enums for constants

Target features constants from loongarch-def.h are currently defined as macros.
Switch to enums for better look in the debugger.

gcc/ChangeLog:

	* config/loongarch/loongarch-def.h: Define constants with
	enums instead of Macros.

gcc/config/loongarch/loongarch-def.h

@@ -23,12 +23,10 @@ along with GCC; see the file COPYING3.  If not see
     - ISA extensions		(isa_ext),
     - base ABI types		(abi_base),
     - ABI extension types	(abi_ext).
-
-    - code models		      (cmodel)
-    - other command-line switches     (switch)
+    - code models		(cmodel)
 
    These values are primarily used for implementing option handling
-   logic in "loongarch.opt", "loongarch-driver.c" and "loongarch-opt.c".
+   logic in "loongarch.opt", "loongarch-driver.cc" and "loongarch-opt.cc".
 
    As for the result of this option handling process, the following
    scheme is adopted to represent the final configuration:
@@ -53,30 +51,40 @@ along with GCC; see the file COPYING3.  If not see
 #include "loongarch-def-array.h"
 #include "loongarch-tune.h"
 
-/* enum isa_base */
 
-/* LoongArch64 */
-#define ISA_BASE_LA64	      0
-#define N_ISA_BASE_TYPES      1
+/* ISA base */
+enum {
+  ISA_BASE_LA64		= 0,  /* LoongArch64 */
+  N_ISA_BASE_TYPES	= 1
+};
+
 extern loongarch_def_array<const char *, N_ISA_BASE_TYPES>
   loongarch_isa_base_strings;
 
-/* enum isa_ext_* */
-#define ISA_EXT_NONE	      0
-#define ISA_EXT_FPU32	      1
-#define ISA_EXT_FPU64	      2
-#define N_ISA_EXT_FPU_TYPES   3
-#define ISA_EXT_SIMD_LSX      3
-#define ISA_EXT_SIMD_LASX     4
-#define N_ISA_EXT_TYPES	      5
+
+/* ISA extensions */
+enum {
+  ISA_EXT_NONE		= 0,
+  ISA_EXT_FPU32		= 1,
+  ISA_EXT_FPU64		= 2,
+  N_ISA_EXT_FPU_TYPES   = 3,
+  ISA_EXT_SIMD_LSX      = 3,
+  ISA_EXT_SIMD_LASX     = 4,
+  N_ISA_EXT_TYPES	= 5
+};
+
 extern loongarch_def_array<const char *, N_ISA_EXT_TYPES>
   loongarch_isa_ext_strings;
 
-/* enum abi_base */
-#define ABI_BASE_LP64D	      0
-#define ABI_BASE_LP64F	      1
-#define ABI_BASE_LP64S	      2
-#define N_ABI_BASE_TYPES      3
+
+/* Base ABI */
+enum {
+  ABI_BASE_LP64D	= 0,
+  ABI_BASE_LP64F	= 1,
+  ABI_BASE_LP64S	= 2,
+  N_ABI_BASE_TYPES	= 3
+};
+
 extern loongarch_def_array<const char *, N_ABI_BASE_TYPES>
   loongarch_abi_base_strings;
 
@@ -90,28 +98,38 @@ extern loongarch_def_array<const char *, N_ABI_BASE_TYPES>
   (abi_base == ABI_BASE_LP64S)
 
 
-/* enum abi_ext */
-#define ABI_EXT_BASE	      0
-#define N_ABI_EXT_TYPES	      1
+/* ABI Extension */
+enum {
+  ABI_EXT_BASE		= 0,
+  N_ABI_EXT_TYPES	= 1
+};
+
 extern loongarch_def_array<const char *, N_ABI_EXT_TYPES>
   loongarch_abi_ext_strings;
 
-/* enum cmodel */
-#define CMODEL_NORMAL	      0
-#define CMODEL_TINY	      1
-#define CMODEL_TINY_STATIC    2
-#define CMODEL_MEDIUM	      3
-#define CMODEL_LARGE	      4
-#define CMODEL_EXTREME	      5
-#define N_CMODEL_TYPES	      6
+
+/* Code Model */
+enum {
+  CMODEL_NORMAL		= 0,
+  CMODEL_TINY		= 1,
+  CMODEL_TINY_STATIC	= 2,
+  CMODEL_MEDIUM		= 3,
+  CMODEL_LARGE		= 4,
+  CMODEL_EXTREME	= 5,
+  N_CMODEL_TYPES	= 6
+};
+
 extern loongarch_def_array<const char *, N_CMODEL_TYPES>
   loongarch_cmodel_strings;
 
-/* enum explicit_relocs */
-#define EXPLICIT_RELOCS_AUTO	0
-#define EXPLICIT_RELOCS_NONE	1
-#define EXPLICIT_RELOCS_ALWAYS	2
-#define N_EXPLICIT_RELOCS_TYPES	3
+
+/* Explicit Reloc Type */
+enum {
+  EXPLICIT_RELOCS_AUTO	    = 0,
+  EXPLICIT_RELOCS_NONE	    = 1,
+  EXPLICIT_RELOCS_ALWAYS    = 2,
+  N_EXPLICIT_RELOCS_TYPES   = 3
+};
 
 /* The common default value for variables whose assignments
    are triggered by command-line options.  */
@@ -159,17 +177,18 @@ struct loongarch_target
   int cmodel;	    /* CMODEL_ */
 };
 
-/* CPU properties.  */
-/* index */
-#define CPU_NATIVE	  0
-#define CPU_ABI_DEFAULT   1
-#define CPU_LOONGARCH64	  2
-#define CPU_LA464	  3
-#define CPU_LA664	  4
-#define N_ARCH_TYPES	  5
-#define N_TUNE_TYPES	  5
+/* CPU model */
+enum {
+  CPU_NATIVE	    = 0,
+  CPU_ABI_DEFAULT   = 1,
+  CPU_LOONGARCH64   = 2,
+  CPU_LA464	    = 3,
+  CPU_LA664	    = 4,
+  N_ARCH_TYPES	    = 5,
+  N_TUNE_TYPES	    = 5
+};
 
-/* parallel tables.  */
+/* CPU model properties */
 extern loongarch_def_array<const char *, N_ARCH_TYPES>
   loongarch_cpu_strings;
 extern loongarch_def_array<loongarch_isa, N_ARCH_TYPES>