Not-linux hosts does not support PLPA.
Since htop works also without it, why not?

Original patch from FreeBSD by Yi-Jheng Lin <yzlin@cs.nctu.edu.tw>
Modified to be conditional by Timothy Redaelli <drizzt@gentoo.org>

https://bugs.gentoo.org/220469

--- configure.ac
+++ configure.ac
@@ -97,8 +97,9 @@
 
 PLPA_INCLUDED(plpa-1.1)
 PLPA_INIT(plpa_happy=yes, plpa_happy=no)
-if test "x$plpa_happy" = xno; then
-   AC_MSG_ERROR([Failed to initialize PLPA.])
+AM_CONDITIONAL([HAVE_PLPA], [test "$plpa_happy" = "yes"])
+if test "$plpa_happy" = "yes"; then
+   AC_DEFINE([HAVE_PLPA], [1], [Have plpa])
 fi
 
 AC_CONFIG_FILES([Makefile])
--- htop.c
+++ htop.c
@@ -112,9 +112,11 @@
    mvaddstr(15, 0, "   F9 k: kill process/tagged processes      P: sort by CPU%");
    mvaddstr(16, 0, " + [ F7: lower priority (+ nice)            M: sort by MEM%");
    mvaddstr(17, 0, " - ] F8: higher priority (root only)        T: sort by TIME");
+#ifdef HAVE_PLPA
    if (pl->processorCount > 1)
       mvaddstr(18, 0, "      a: set CPU affinity                F4 I: invert sort order");
    else
+#endif
       mvaddstr(18, 0, "                                         F4 I: invert sort order");
    mvaddstr(19, 0, "   F2 S: setup                           F6 >: select sort column");
    mvaddstr(20, 0, "   F1 h: show this help screen");
@@ -131,8 +133,10 @@
    mvaddstr(16, 0, " + [ F7"); mvaddstr(16,40, "    M");
    mvaddstr(17, 0, " - ] F8"); mvaddstr(17,40, "    T");
                                mvaddstr(18,40, " F4 I");
+#if HAVE_PLPA
    if (pl->processorCount > 1)
       mvaddstr(18, 0, "      a:");
+#endif
    mvaddstr(19, 0, "   F2 S"); mvaddstr(19,40, " F6 >");
    mvaddstr(20, 0, "   F1 h");
    mvaddstr(21, 0, "  F10 q"); mvaddstr(21,40, "    s");
@@ -630,6 +634,7 @@
          refreshTimeout = 0;
          break;
       }
+#ifdef HAVE_PLPA
       case 'a':
       {
          if (pl->processorCount == 1)
@@ -665,6 +670,7 @@
          refreshTimeout = 0;
          break;
       }
+#endif
       case KEY_F(10):
       case 'q':
          quit = 1;
--- Process.c
+++ Process.c
@@ -28,7 +28,9 @@
 #include <pwd.h>
 #include <sched.h>
 
+#ifdef HAVE_PLPA
 #include <plpa.h>
+#endif
 
 // This works only with glibc 2.1+. On earlier versions
 // the behavior is similar to have a hardcoded page size.
@@ -493,6 +495,7 @@
    return (err == 0);
 }
 
+#ifdef HAVE_PLPA
 unsigned long Process_getAffinity(Process* this) {
    unsigned long mask = 0;
    plpa_sched_getaffinity(this->pid, sizeof(unsigned long), (plpa_cpu_set_t*) &mask);
@@ -502,6 +505,7 @@
 bool Process_setAffinity(Process* this, unsigned long mask) {
    return (plpa_sched_setaffinity(this->pid, sizeof(unsigned long), (plpa_cpu_set_t*) &mask) == 0);
 }
+#endif
 
 void Process_sendSignal(Process* this, int signal) {
    kill(this->pid, signal);
--- Makefile.am
+++ Makefile.am
@@ -1,5 +1,7 @@
 
+if HAVE_PLPA
 SUBDIRS = plpa-1.1
+endif
 
 bin_PROGRAMS = htop
 dist_man_MANS = htop.1
@@ -35,7 +37,9 @@
 
 BUILT_SOURCES = $(myhtopheaders)
 htop_SOURCES = $(myhtopheaders) $(myhtopsources) config.h debug.h
+if HAVE_PLPA
 htop_LDADD = $(top_builddir)/plpa-1.1/src/libplpa_included.la
+endif
 
 profile:
 	$(MAKE) all CFLAGS="-pg -O2"