(Re-)enable building on illumos (SmartOS, OmniOS, ...) and Solaris

Changes

@@ -101,6 +101,12 @@ Working version
   (Gabriel Scherer, review by Sébastien Hinderer and David Allsopp,
    report by Ralph Seichter)
 
+- #10063: (Re-)enable building on illumos (SmartOS, OmniOS, ...) and
+  Oracle Solaris; x86_64/GCC and 64-bit SPARC/Sun PRO C compilers.
+  (partially revert #2024).
+  (Tõivo Leedjärv and Konstantin Romanov,
+   review by Gabriel Scherer, Sébastien Hinderer and Xavier Leroy)
+
 ### Bug fixes:
 
 - #10005: Try expanding aliases in Ctype.nondep_type_rec

INSTALL.adoc

@@ -57,6 +57,12 @@ By default, build is 32-bit. For 64-bit build, please set environment variable `
   for _both_ `configure` and `make world` phases. Note, if this variable is set for only one phase,
   your build will break (`ocamlrun` segfaults).
 +
+* For Solaris/Illumos on SPARC machines with Sun PRO compiler only 64-bit
+  bytecode target is supported (32-bit fails due to alignment issues; the optimization
+  is preset to `-O4` for inlining):
+
+    ./configure CC="cc -m64"
++
 If something goes wrong during the automatic configuration, or if the generated
 files cause errors later on, then look at the template files:
 

Makefile.config.in

@@ -172,6 +172,7 @@ OTHERLIBRARIES=@otherlibraries@
 # Needed for the "systhreads" package
 PTHREAD_LINK=@pthread_link@
 PTHREAD_CAML_LINK=$(addprefix -cclib ,$(PTHREAD_LINK))
+PTHREAD_CFLAGS=@PTHREAD_CFLAGS@
 
 UNIX_OR_WIN32=@unix_or_win32@
 UNIXLIB=@unixlib@

aclocal.m4

@@ -51,6 +51,8 @@ clang __clang_major__ __clang_minor__
 gcc __GNUC__ __GNUC_MINOR__
 #elif defined(__xlc__) && defined(__xlC__)
 xlc __xlC__ __xlC_ver__
+#elif defined(__SUNPRO_C)
+sunc __SUNPRO_C __SUNPRO_C
 #else
 unknown
 #endif]