gnu: gcc: Fix build with glibc >= 2.28.

* gnu/packages/patches/gcc-libsanitizer-ustat.patch: New file.
* gnu/local.mk (dist_patch_DATA): Register it.
* gnu/packages/gcc.scm (gcc-5)[source](patches): Add it.

gnu/local.mk

@@ -690,6 +690,7 @@ dist_patch_DATA =						\
   %D%/packages/patches/gcc-fix-texi2pod.patch			\
   %D%/packages/patches/gcc-4.9-libsanitizer-fix.patch		\
   %D%/packages/patches/gcc-libsanitizer-fix.patch		\
+  %D%/packages/patches/gcc-libsanitizer-ustat.patch		\
   %D%/packages/patches/gcc-libvtv-runpath.patch			\
   %D%/packages/patches/gcc-strmov-store-file-names.patch	\
   %D%/packages/patches/gcc-4-compile-with-gcc-5.patch		 \

gnu/packages/gcc.scm

@@ -431,6 +431,7 @@ Go.  It also includes runtime support libraries for these languages.")
                (base32
                 "11zd1hgzkli3b2v70qsm2hyqppngd4616qc96lmm9zl2kl9yl32k"))
               (patches (search-patches "gcc-arm-bug-71399.patch"
+                                       "gcc-libsanitizer-ustat.patch"
                                        "gcc-strmov-store-file-names.patch"
                                        "gcc-5.0-libvtv-runpath.patch"
                                        "gcc-5-source-date-epoch-1.patch"

gnu/packages/patches/gcc-libsanitizer-ustat.patch

@@ -0,0 +1,41 @@
+Remove use of deprecated ustat interface in glibc 2.28:
+
+https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85835
+
+Taken from upstream:
+
+https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=260684
+
+diff --git a/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc b/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc
+index 858bb2184505..de18e56d11cf 100644
+--- a/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc
++++ b/libsanitizer/sanitizer_common/sanitizer_platform_limits_posix.cc
+@@ -157,7 +157,6 @@ typedef struct user_fpregs elf_fpregset_t;
+ # include <sys/procfs.h>
+ #endif
+ #include <sys/user.h>
+-#include <sys/ustat.h>
+ #include <linux/cyclades.h>
+ #include <linux/if_eql.h>
+ #include <linux/if_plip.h>
+@@ -250,7 +249,19 @@ namespace __sanitizer {
+ #endif // SANITIZER_LINUX || SANITIZER_FREEBSD
+ 
+ #if SANITIZER_LINUX && !SANITIZER_ANDROID
+-  unsigned struct_ustat_sz = sizeof(struct ustat);
++  // Use pre-computed size of struct ustat to avoid <sys/ustat.h> which
++  // has been removed from glibc 2.28.
++#if defined(__aarch64__) || defined(__s390x__) || defined (__mips64) \
++  || defined(__powerpc64__) || defined(__arch64__) || defined(__sparcv9) \
++  || defined(__x86_64__)
++#define SIZEOF_STRUCT_USTAT 32
++#elif defined(__arm__) || defined(__i386__) || defined(__mips__) \
++  || defined(__powerpc__) || defined(__s390__)
++#define SIZEOF_STRUCT_USTAT 20
++#else
++#error Unknown size of struct ustat
++#endif
++  unsigned struct_ustat_sz = SIZEOF_STRUCT_USTAT;
+   unsigned struct_rlimit64_sz = sizeof(struct rlimit64);
+   unsigned struct_statvfs64_sz = sizeof(struct statvfs64);
+ #endif // SANITIZER_LINUX && !SANITIZER_ANDROID