sparc: Remove register storage class in sparc.c

sparc: Remove register storage class in sparc.c

The switch to C++17 broke SPARC bootstrap:

/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c:8887:34: error: ISO C++17 does not allow 'register' storage class specifier [-Werror=register]
 8887 | epilogue_renumber (register rtx *where, int test)
      |                                  ^~~~~
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c: In function 'int epilogue_renumber(rtx_def**, int)':
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c:8889:24: error: ISO C++17 does not allow 'register' storage class specifier [-Werror=register]
 8889 |   register const char *fmt;
      |                        ^~~
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c:8890:16: error: ISO C++17 does not allow 'register' storage class specifier [-Werror=register]
 8890 |   register int i;
      |                ^
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c:8891:26: error: ISO C++17 does not allow 'register' storage class specifier [-Werror=register]
 8891 |   register enum rtx_code code;
      |                          ^~~~
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c:8948:17: error: ISO C++17 does not allow 'register' storage class specifier [-Werror=register]
 8948 |    register int j;
      |                 ^
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c: In function 'void sparc_print_operand_address(std::FILE*, machine_mode, rtx)':
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c:9671:16: error: ISO C++17 does not allow 'register' storage class specifier [-Werror=register]
 9671 |   register rtx base, index = 0;
      |                ^~~~
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c:9671:22: error: ISO C++17 does not allow 'register' storage class specifier [-Werror=register]
 9671 |   register rtx base, index = 0;
      |                      ^~~~~
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c:9673:16: error: ISO C++17 does not allow 'register' storage class specifier [-Werror=register]
 9673 |   register rtx addr = x;
      |                ^~~~
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c: At global scope:
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c:9807:32: error: ISO C++17 does not allow 'register' storage class specifier [-Werror=register]
 9807 | sparc_type_code (register tree type)
      |                                ^~~~
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c: In function 'long unsigned int sparc_type_code(tree)':
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c:9809:26: error: ISO C++17 does not allow 'register' storage class specifier [-Werror=register]
 9809 |   register unsigned long qualifiers = 0;
      |                          ^~~~~~~~~~
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c:9810:21: error: ISO C++17 does not allow 'register' storage class specifier [-Werror=register]
 9810 |   register unsigned shift;
      |                     ^~~~~
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c: In function 'int set_extends(rtx_insn*)':
/vol/gcc/src/hg/master/local/gcc/config/sparc/sparc.c:10306:16: error: ISO C++17 does not allow 'register' storage class specifier [-Werror=register]
10306 |   register rtx pat = PATTERN (insn);
      |                ^~~

Fixed by removing the register keyword.  Bootstrapped on
sparc-sun-solaris2.11.

	* config/sparc/sparc.c (epilogue_renumber): Remove register.
	(sparc_print_operand_address): Likewise.
	(sparc_type_code): Likewise.
	(set_extends): Likewise.