Revert "glibc: Patch to work around missing features in LLVM's s390x assembler."

This reverts commit b230e4f.

Closes #21329.

Author: alexrp

Diff for: lib/libc/glibc/sysdeps/s390/s390-64/start-2.33.S

@@ -61,8 +61,7 @@
 _start:
 	cfi_startproc
 	/* Mark r14 as undefined in order to stop unwinding here!  */
-	/* zig patch: r14 -> %r14. revert with llvm 20. */
-	cfi_undefined (%r14)
+	cfi_undefined (r14)
 	/* Load argc and argv from stack.  */
 	la	%r4,8(%r15)		# get argv
 	lg	%r3,0(%r15)		# get argc
@@ -86,8 +85,7 @@ _start:
 
 	/* Ok, now branch to the libc main routine.  */
 #ifdef PIC
-	/* zig patch: GOTENT -> GOT. revert with llvm 20. */
-	larl	%r2,main@GOT		# load pointer to main
+	larl	%r2,main@GOTENT		# load pointer to main
 	lg	%r2,0(%r2)
 	brasl	%r14,__libc_start_main@plt
 #else

Diff for: lib/libc/glibc/sysdeps/s390/s390-64/start.S

@@ -60,8 +60,7 @@
 _start:
 	cfi_startproc
 	/* Mark r14 as undefined in order to stop unwinding here!  */
-	/* zig patch: r14 -> %r14. revert with llvm 20. */
-	cfi_undefined (%r14)
+	cfi_undefined (r14)
 	/* Load argc and argv from stack.  */
 	la	%r4,8(%r15)		# get argv
 	lg	%r3,0(%r15)		# get argc
@@ -88,8 +87,7 @@ _start:
 # ifdef SHARED
 	/* Used for dynamic linked position independent executable.
 	   => Scrt1.o  */
-	/* zig patch: GOTENT -> GOT. revert with llvm 20. */
-	larl	%r2,main@GOT		# load pointer to main
+	larl	%r2,main@GOTENT		# load pointer to main
 	lg	%r2,0(%r2)
 # else
 	/* Used for dynamic linked position dependent executable.
@@ -121,8 +119,7 @@ _start:
 	   use of GOT relocations before __libc_start_main is called.  */
 __wrap_main:
 	cfi_startproc
-	/* zig patch: GOTENT -> GOT. revert with llvm 20. */
-	larl	%r1,main@GOT		# load pointer to main
+	larl	%r1,main@GOTENT		# load pointer to main
 	lg	%r1,0(%r1)
 	br	%r1
 	cfi_endproc