arm: Fix up arm installed unwind.h for use in pedantic modes [PR93615]

As the following testcase shows, unwind.h on ARM can't be (starting with GCC
10) compiled with -std=c* modes, only -std=gnu* modes.
The problem is it uses asm keyword, which isn't a keyword in those modes
(system headers vs. non-system ones don't make a difference here).
glibc and other installed headers use __asm or __asm__ keywords instead that
work fine in both standard and gnu modes.

While there, as it is an installed header, I think it is also wrong to
completely ignore any identifier namespace rules.
The generic unwind.h defines just _Unwind* namespace identifiers plus
_sleb128_t/_uleb128_t (but e.g. unlike libstdc++/glibc headers doesn't
uglify operand names), the ARM unwind.h is much worse here.  I've just
changed the gnu_Unwind_Find_got function at least not be in user identifier
namespace, but perhaps it would be good to go further and rename e.g.
or e.g.
  typedef _Unwind_Reason_Code (*personality_routine) (_Unwind_State,
      _Unwind_Control_Block *, _Unwind_Context *);
in unwind-arm-common.h.

2020-02-07  Jakub Jelinek  <jakub@redhat.com>

	PR target/93615
	* config/arm/unwind-arm.h (gnu_Unwind_Find_got): Rename to ...
	(_Unwind_gnu_Find_got): ... this.  Use __asm instead of asm.  Remove
	trailing :s in asm.  Formatting fixes.
	(_Unwind_decode_typeinfo_ptr): Adjust caller.

	* gcc.dg/pr93615.c: New test.

gcc/testsuite/ChangeLog

 2020-02-07  Jakub Jelinek  <jakub@redhat.com>
 
+	PR target/93615
+	* gcc.dg/pr93615.c: New test.
+
 	PR target/93611
 	* gcc.target/i386/pr93611.c: New test.
 

gcc/testsuite/gcc.dg/pr93615.c

+/* { dg-do compile } */
+/* { dg-options "-std=c11" } */
+/* { dg-require-effective-target exceptions } */
+
+#include <unwind.h>
+
+int
+main ()
+{
+  return 0;
+}

libgcc/ChangeLog

+2020-02-07  Jakub Jelinek  <jakub@redhat.com>
+
+	PR target/93615
+	* config/arm/unwind-arm.h (gnu_Unwind_Find_got): Rename to ...
+	(_Unwind_gnu_Find_got): ... this.  Use __asm instead of asm.  Remove
+	trailing :s in asm.  Formatting fixes.
+	(_Unwind_decode_typeinfo_ptr): Adjust caller.
+
 2020-01-31  Sandra Loosemore  <sandra@codesourcery.com>
 
 	nios2: Support for GOT-relative DW_EH_PE_datarel encoding.

libgcc/config/arm/unwind-arm.h

@@ -43,19 +43,15 @@ extern "C" {
 #endif
 _Unwind_Ptr __attribute__((weak)) __gnu_Unwind_Find_got (_Unwind_Ptr);
 
-static inline _Unwind_Ptr gnu_Unwind_Find_got (_Unwind_Ptr ptr)
+static inline _Unwind_Ptr _Unwind_gnu_Find_got (_Unwind_Ptr ptr)
 {
     _Unwind_Ptr res;
 
     if (__gnu_Unwind_Find_got)
-	res =  __gnu_Unwind_Find_got (ptr);
+	res = __gnu_Unwind_Find_got (ptr);
     else
-      {
-	asm volatile ("mov %[result], r" XSTR(FDPIC_REGNUM)
-		      : [result]"=r" (res)
-		      :
-		      :);
-      }
+	__asm volatile ("mov %[result], r" XSTR(FDPIC_REGNUM)
+			: [result] "=r" (res));
 
     return res;
 }
@@ -75,7 +71,7 @@ static inline _Unwind_Ptr gnu_Unwind_Find_got (_Unwind_Ptr ptr)
 #if __FDPIC__
       /* For FDPIC, we store the offset of the GOT entry.  */
       /* So, first get GOT from dynamic linker and then use indirect access.  */
-      tmp += gnu_Unwind_Find_got (ptr);
+      tmp += _Unwind_gnu_Find_got (ptr);
       tmp = *(_Unwind_Word *) tmp;
 #elif (defined(linux) && !defined(__uClinux__)) || defined(__NetBSD__) \
     || defined(__FreeBSD__) || defined(__fuchsia__)