Import Solaris support (#741)

This commit adds support for Solaris, squashed from PR #741:

Summary of additions:

* Initial setup of Solaris platform directory
* Add Solaris platform into autoconf template
* Uptime and load averages
* Add dependency on libkstat
* Basic process listing
* Zone name display
* CPU detection
* Per-process memory and CPU usage parsed correctly
* Uses sysconf to discover number of CPUs, instead of more complex libkstat code
* Simple memory display working
* Reduce repetitive calls to the PAGE_SIZE macro when reading memory info
* Add Project, Contract, Task, and Pool into process properties
* Use system major()/minor() implementations and remove extraneous definition of mkdev()
* Get the STARTTIME column working properly, using the Linux implementation as a guide
diff --git a/configure.ac b/configure.ac
index 3d69756..bf7b4c9 100644
--- a/configure.ac
+++ b/configure.ac
@@ -43,6 +43,9 @@
 darwin*)
    my_htop_platform=darwin
    ;;
+solaris*)
+   my_htop_platform=solaris
+   ;;
 *)
    my_htop_platform=unsupported
    ;;
@@ -238,6 +241,10 @@
    AC_CHECK_LIB([kvm], [kvm_open], [], [missing_libraries="$missing_libraries libkvm"])
 fi
 
+if test "$my_htop_platform" = "solaris"; then
+   AC_CHECK_LIB([kstat], [kstat_open], [], [missing_libraries="$missing_libraries libkstat"])
+fi
+
 AC_ARG_ENABLE(linux_affinity, [AS_HELP_STRING([--enable-linux-affinity], [enable Linux sched_setaffinity and sched_getaffinity for affinity support, disables hwloc])], ,enable_linux_affinity="yes")
 if test "x$enable_linux_affinity" = xyes -a "x$cross_compiling" = xno; then
    AC_MSG_CHECKING([for usable sched_setaffinity])
@@ -302,6 +309,7 @@
 AM_CONDITIONAL([HTOP_DRAGONFLYBSD], [test "$my_htop_platform" = dragonflybsd])
 AM_CONDITIONAL([HTOP_OPENBSD], [test "$my_htop_platform" = openbsd])
 AM_CONDITIONAL([HTOP_DARWIN], [test "$my_htop_platform" = darwin])
+AM_CONDITIONAL([HTOP_SOLARIS], [test "$my_htop_platform" = solaris])
 AM_CONDITIONAL([HTOP_UNSUPPORTED], [test "$my_htop_platform" = unsupported])
 AC_SUBST(my_htop_platform)
 AC_CONFIG_FILES([Makefile htop.1])