nptl:arm: add a wrapper for .cfi_sections pseudo-ops

ARM disables by default the support for ASM CFI directives.
Anyway using an old version of binutils that does not support some new
pseudo-op, the build fails as below:

  AS libpthread/nptl/sysdeps/unix/sysv/linux/close.oS
libpthread/nptl/sysdeps/unix/sysv/linux/close.S: Assembler messages:
libpthread/nptl/sysdeps/unix/sysv/linux/close.S:9: Error: unknown pseudo-op: `.cfi_sections'

The problem is that the .cfi_sections pseudo should be wrapped by a macro
that expands to nothing when the CFI is off.

Signed-off-by: Carmelo Amoroso <carmelo.amoroso@st.com>
CC: Khem Ray <ray.khem@gmail.com>

libc/sysdeps/linux/common/sysdep.h

@@ -51,6 +51,7 @@
 
 /* Macros to generate eh_frame unwind information.  */
 # ifdef HAVE_ASM_CFI_DIRECTIVES
+#  define cfi_sections(sect...) 	.cfi_sections sect
 #  define cfi_startproc			.cfi_startproc
 #  define cfi_endproc			.cfi_endproc
 #  define cfi_def_cfa(reg, off)		.cfi_def_cfa reg, off
@@ -71,6 +72,7 @@
 #  define cfi_lsda(enc, exp)		.cfi_lsda enc, exp
 
 # else
+#  define cfi_sections(sect...)
 #  define cfi_startproc
 #  define cfi_endproc
 #  define cfi_def_cfa(reg, off)
@@ -95,6 +97,8 @@
 # ifdef HAVE_ASM_CFI_DIRECTIVES
 #  define CFI_STRINGIFY(Name) CFI_STRINGIFY2 (Name)
 #  define CFI_STRINGIFY2(Name) #Name
+#  define CFI_SECTIONS(sect...) \
+   ".cfi_sections " CFI_STRINGIFY(sect)
 #  define CFI_STARTPROC	".cfi_startproc"
 #  define CFI_ENDPROC	".cfi_endproc"
 #  define CFI_DEF_CFA(reg, off)	\
@@ -128,6 +132,7 @@
 #  define CFI_LSDA(enc, exp) \
    ".cfi_lsda " CFI_STRINGIFY(enc) "," CFI_STRINGIFY(exp)
 # else
+#  define CFI_SECTIONS(sect...)
 #  define CFI_STARTPROC
 #  define CFI_ENDPROC
 #  define CFI_DEF_CFA(reg, off)

libpthread/nptl/sysdeps/unix/sysv/linux/arm/sysdep-cancel.h

@@ -36,7 +36,7 @@
   .type __##syscall_name##_nocancel,%function;				\
   .globl __##syscall_name##_nocancel;					\
   __##syscall_name##_nocancel:						\
-    .cfi_sections .debug_frame;						\
+    cfi_sections(.debug_frame);						\
     cfi_startproc;							\
     DO_CALL (syscall_name, args);					\
     PSEUDO_RET;								\

libpthread/nptl/sysdeps/unix/sysv/linux/arm/unwind-resume.c

@@ -65,7 +65,7 @@ __asm__ (
 "	.globl	_Unwind_Resume\n"
 "	.type	_Unwind_Resume, %function\n"
 "_Unwind_Resume:\n"
-"	.cfi_sections .debug_frame\n"
+"	" CFI_SECTIONS (.debug_frame) "\n"
 "	" CFI_STARTPROC "\n"
 "	stmfd	sp!, {r4, r5, r6, lr}\n"
 "	" CFI_ADJUST_CFA_OFFSET (16)" \n"