mcheck: Align struct hdr to MALLOC_ALIGNMENT bytes [BZ #28068]

1. Align struct hdr to MALLOC_ALIGNMENT bytes so that malloc hooks in
libmcheck align memory to MALLOC_ALIGNMENT bytes.
2. Remove tst-mallocalign1 from tests-exclude-mcheck for i386 and x32.
3. Add tst-pvalloc-fortify and tst-reallocarray to tests-exclude-mcheck
since they use malloc_usable_size (see BZ #22057).

This fixed BZ #28068.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

malloc/Makefile

@@ -95,7 +95,9 @@ tests-exclude-mcheck = tst-mallocstate \
 	tst-malloc_info \
 	tst-memalign \
 	tst-posix_memalign \
-	tst-realloc
+	tst-realloc \
+	tst-pvalloc-fortify \
+	tst-reallocarray
 
 tests-mcheck = $(filter-out $(tests-exclude-mcheck), $(tests))
 

malloc/mcheck.c

@@ -20,6 +20,7 @@
 #ifndef _MALLOC_INTERNAL
 # define _MALLOC_INTERNAL
 # include <malloc.h>
+# include <malloc-size.h>
 # include <mcheck.h>
 # include <stdint.h>
 # include <stdio.h>
@@ -53,7 +54,7 @@ struct hdr
   struct hdr *next;
   void *block;                  /* Real block allocated, for memalign.  */
   unsigned long int magic2;     /* Extra, keeps us doubleword aligned.  */
-};
+} __attribute__ ((aligned (MALLOC_ALIGNMENT)));
 
 /* This is the beginning of the list of all memory blocks allocated.
    It is only constructed if the pedantic testing is requested.  */

sysdeps/i386/Makefile

@@ -5,10 +5,6 @@ asm-CPPFLAGS += -DGAS_SYNTAX
 # The i386 `long double' is a distinct type we support.
 long-double-fcts = yes
 
-ifeq ($(subdir),malloc)
-tests-exclude-mcheck += tst-mallocalign1
-endif
-
 ifeq ($(subdir),math)
 # These functions change the rounding mode internally and need to
 # update both the SSE2 rounding mode and the 387 rounding mode.  See

sysdeps/x86_64/x32/Makefile

@@ -1,7 +1,3 @@
-ifeq ($(subdir),malloc)
-tests-exclude-mcheck += tst-mallocalign1
-endif
-
 ifeq ($(subdir),math)
 # Since x32 returns 32-bit long int and 64-bit long long int in the
 # same 64-bit register, we make the 32b-bit lround an alias of the