Fix these fails:
alpha-dec-vms +FAIL: ld-scripts/asciz
alpha-dec-vms +FAIL: ld-scripts/ascii
i386-go32 +FAIL: ld-scripts/asciz
sh-coff +FAIL: ld-scripts/asciz
It's better to positively select targets for .section support than to
try to exclude all targets that don't. Make a new is_coff_format so
we can easily select such.
binutils/
* testsuite/lib/binutils-common.exp (is_coff_format): New.
ld/
* testsuite/ld-scripts/ascii.d: Use is_elf_format and
is_coff_format to select targets, exclude ti coff.
* testsuite/ld-scripts/asciz.d: Likewise. Accept trailing zeros.
* ldlex.l: Add ASCII token.
* ldgram.y: Add parsing of the ASCII command.
* ldlang.c (lang_add_string): Add maximum size parameter. Move escape character handling code into separate function.
* ldlang.h (lang_add_string): Update prototype.
* NEWS: Mention the new feature.
* ld.texi (Output Section Data): Document the new directives.
* testsuite/ld-scripts/asciz.t: Adjust to work on more architectures and to test more aspects of the ASCIZ directive.
* testsuite/ld-scripts/asciz.d: Adjust to match the changes to the test linker script.
* testsuite/ld-scripts/ascii.d: New test driver.
* testsuite/ld-scripts/ascii.s: New test assembler source.
* testsuite/ld-scripts/ascii.t: New test script.
* testsuite/ld-scripts/script.exp: Run the new test.
