salvaging 183105 from dead client

a number of fixes for arm elf generation in 5l. -T now works as
advertised, -D now works properly.

R=rsc
CC=golang-dev
https://golang.org/cl/194076

src/cmd/5l/asm.c

@@ -301,13 +301,14 @@ asmb(void)
 			wputl(5);			/* # of Shdrs */
 		wputl(4);			/* Shdr with strings */
 
-		fo = 0;
-		va = INITTEXT & ~((vlong)INITRND - 1);
-		w = HEADR+textsize;
+		fo = HEADR;
+		va = rnd(INITTEXT, INITRND);
+
+		w = textsize;
 
 		linuxphdr(1,			/* text - type = PT_LOAD */
 			1L+4L,			/* text - flags = PF_X+PF_R */
-			0,			/* file offset */
+			fo,			/* file offset */
 			va,			/* vaddr */
 			va,			/* paddr */
 			w,			/* file size */
@@ -360,7 +361,7 @@ asmb(void)
 
 		stroffset = 1;  /* 0 means no name, so start at 1 */
 		fo = HEADR;
-		va = (INITTEXT & ~((vlong)INITRND - 1)) + HEADR;
+		va = rnd(INITTEXT, INITRND);
 		w = textsize;
 
 		linuxshdr(".text",		/* name */

src/cmd/5l/doc.go

@@ -19,10 +19,10 @@ Major changes include:
 Original options are listed in the link above.
 
 Options new in this version:
+
 -L dir1,dir2,..
 	Search for libraries (package files) in the comma-separated list of directories.
 	The default is the single location $GOROOT/pkg/$GOOS_arm.
 
-
 */
 package documentation

src/cmd/5l/obj.c

@@ -80,7 +80,7 @@ linkername[] =
 void
 usage(void)
 {
-	fprint(2, "usage: 5l [-options] main.5\n");
+	fprint(2, "usage: 5l [-E entry] [-H head] [-L dir] [-T text] [-D data] [-R rnd] [-o out] main.5\n");
 	errorexit();
 }
 
@@ -221,7 +221,7 @@ main(int argc, char *argv[])
 	case 6:	/* arm elf */
 		HEADR = linuxheadr();
 		if(INITTEXT == -1)
-			INITTEXT = 0x8000+HEADR;
+			INITTEXT = 0x8000;
 		if(INITDAT == -1)
 			INITDAT = 0;
 		if(INITRND == -1)