ASCIZ Command for output section

Adds a new directive to the linker script syntax: ASCIZ.
This inserts a zero-terminated string into the output at the place where it is used.

ld/testsuite/ld-scripts/asciz.d

@@ -0,0 +1,17 @@
+#source: asciz.s
+#ld: -T asciz.t
+#objdump: -s -j .text
+#target: [is_elf_format]
+#skip: mips*-*-*
+#skip: tilegx*-*-* tilepro-*-*
+# COFF, PE and MIPS targets align code to a 16 byte boundary
+# tilegx andtilepro aligns code to a 8 byte boundary.
+
+.*:     file format .*
+
+Contents of section .text:
+ .... 01010101 54686973 20697320 61207374  ....This is a st
+ .... 72696e67 00...... ........ ........  ring............
+ .... 54686973 20697320 616e6f74 68657220  This is another 
+ .... 0a737472 696e6753 00                 .stringS........
+#pass

ld/testsuite/ld-scripts/asciz.s

@@ -0,0 +1,8 @@
+	.section .text
+	.long 0x01010101
+	
+	.section .data
+	.long 0x9abcdef0
+	
+	.section .bss
+	.long 0

ld/testsuite/ld-scripts/asciz.t

@@ -0,0 +1,23 @@
+MEMORY {
+  rom : ORIGIN = 0x00000, LENGTH = 0x10000
+  ram : ORIGIN = 0x10000, LENGTH = 0x10000
+}
+
+_start = 0x000000;
+SECTIONS
+{
+  . = 0x1000 + SIZEOF_HEADERS;
+  .text ALIGN (0x20) :
+    {
+      *(.text)
+      ASCIZ "This is a string"
+      . = ALIGN(0x20);
+      align_label = .;
+      ASCIZ "This is another \nstring\123"
+      unalign_label = .;
+    }
+  .data : AT (0x10000) { *(.data) } >ram /* NO default AT>rom */
+  . = ALIGN(0x20);
+  .bss : { *(.bss) } >ram /* NO default AT>rom */
+  /DISCARD/ : { *(*) }
+}

ld/testsuite/ld-scripts/script.exp

@@ -227,6 +227,7 @@ foreach test_script $test_script_list {
     run_dump_test [string range $test_script 0 end-2]
 }
 
+run_dump_test "asciz"
 run_dump_test "align-with-input"
 run_dump_test "pr20302"
 run_dump_test "output-section-types"