[OpenMP] Don't use libproc on Solaris (#142379)

`openmp` currently doesn't compile on 32-bit Solaris:

```
FAILED: projects/openmp/runtime/src/CMakeFiles/omp.dir/z_Linux_util.cpp.o
[...]
In file included from openmp/runtime/src/z_Linux_util.cpp:78:
In file included from /usr/include/libproc.h:25:
In file included from /usr/include/gelf.h:10:
/usr/include/libelf.h:22:2: error: "large files are not supported by libelf"
   22 | #error "large files are not supported by libelf"
      |  ^
In file included from openmp/runtime/src/z_Linux_util.cpp:78:
/usr/include/libproc.h:42:2: error: "Cannot use libproc in the large file compilation environment"
   42 | #error "Cannot use libproc in the large file compilation environment"
      |  ^
```

Looking closer, there's no point in using `Pgrab` (the only interface
from `<libproc.h>`) at all: the resulting `ps_prochandle_t *` isn't used
in the remainder of the code and the original PR #82930 gives no
indication why it is deemed necessary/useful.

While at it, this patch switches to use `/proc/self/xmap`, matching
`compiler-rt`'s `sanitizer_procmaps_solaris.cpp`, and makes some minor
formatting fixes.

Tested on `sparc-sun-solaris2.11`, `sparcv9-sun-solaris2.11`,
`i386-pc-solaris2.11`, and `amd64-pc-solaris2.11`.

Author: rorth

openmp/runtime/cmake/LibompHandleFlags.cmake

@@ -149,9 +149,6 @@ function(libomp_get_libflags libflags)
     endif()
   elseif(${CMAKE_SYSTEM_NAME} MATCHES "Linux|NetBSD|SunOS")
     libomp_append(libflags_local -lm)
-    if (${CMAKE_SYSTEM_NAME} STREQUAL "SunOS")
-      libomp_append(libflags_local "-lproc")
-    endif()
   endif()
   set(libflags_local ${libflags_local} ${LIBOMP_LIBFLAGS})
   libomp_setup_flags(libflags_local)

openmp/runtime/src/z_Linux_util.cpp

@@ -75,7 +75,6 @@
 #include <pthread_np.h>
 #endif
 #elif KMP_OS_SOLARIS
-#include <libproc.h>
 #include <procfs.h>
 #include <thread.h>
 #include <sys/loadavg.h>
@@ -2232,43 +2231,34 @@ int __kmp_is_address_mapped(void *addr) {
 
   kvm_close(fd);
 #elif KMP_OS_SOLARIS
-  prmap_t *cur, *map;
+  prxmap_t *cur, *map;
   void *buf;
   uintptr_t uaddr;
   ssize_t rd;
-  int err;
-  int file;
-
+  int fd;
   pid_t pid = getpid();
-  struct ps_prochandle *fd = Pgrab(pid, PGRAB_RDONLY, &err);
-  ;
-
-  if (!fd) {
-    return 0;
-  }
-
-  char *name = __kmp_str_format("/proc/%d/map", pid);
-  size_t sz = (1 << 20);
-  file = open(name, O_RDONLY);
-  if (file == -1) {
+  char *name = __kmp_str_format("/proc/%d/xmap", pid);
+  fd = open(name, O_RDONLY);
+  if (fd == -1) {
     KMP_INTERNAL_FREE(name);
     return 0;
   }
 
+  size_t sz = (1 << 20);
   buf = KMP_INTERNAL_MALLOC(sz);
 
-  while (sz > 0 && (rd = pread(file, buf, sz, 0)) == sz) {
+  while (sz > 0 && (rd = pread(fd, buf, sz, 0)) == sz) {
     void *newbuf;
     sz <<= 1;
     newbuf = KMP_INTERNAL_REALLOC(buf, sz);
     buf = newbuf;
   }
 
-  map = reinterpret_cast<prmap_t *>(buf);
+  map = reinterpret_cast<prxmap_t *>(buf);
   uaddr = reinterpret_cast<uintptr_t>(addr);
 
   for (cur = map; rd > 0; cur++, rd = -sizeof(*map)) {
-    if ((uaddr >= cur->pr_vaddr) && (uaddr < cur->pr_vaddr)) {
+    if (uaddr >= cur->pr_vaddr && uaddr < cur->pr_vaddr) {
       if ((cur->pr_mflags & MA_READ) != 0 && (cur->pr_mflags & MA_WRITE) != 0) {
         found = 1;
         break;
@@ -2277,7 +2267,7 @@ int __kmp_is_address_mapped(void *addr) {
   }
 
   KMP_INTERNAL_FREE(map);
-  close(file);
+  close(fd);
   KMP_INTERNAL_FREE(name);
 #elif KMP_OS_DARWIN