boost is part of the Fedora, but not of the RHEL Flatpak SDK

(using %global instead of %define became necessary to be able to append to
flatpakoptions)

libreoffice.spec

@@ -1083,7 +1083,10 @@ SMP_MFLAGS=%{?_smp_mflags}
 SMP_MFLAGS=$[${SMP_MFLAGS/-j/}]
 
 %if 0%{?flatpak}
-%define flatpakoptions --with-boost-libdir=%{_libdir} --with-beanshell-jar=/app/share/java/bsh.jar --with-commons-logging-jar=/app/share/java/commons-logging.jar --with-flute-jar=/app/share/java/flute.jar --with-jfreereport-jar=/app/share/java/flow-engine.jar --with-libbase-jar=/app/share/java/libbase.jar --with-libfonts-jar=/app/share/java/libfonts.jar --with-libformula-jar=/app/share/java/libformula.jar --with-liblayout-jar=/app/share/java/liblayout.jar --with-libloader-jar=/app/share/java/libloader.jar --with-librepository-jar=/app/share/java/librepository.jar --with-libserializer-jar=/app/share/java/libserializer.jar --with-libxml-jar=/app/share/java/libxml.jar --with-sac-jar=/app/share/java/sac.jar FIREBIRDCONFIG=%{_libdir}/fb_config QT4INC=%{_includedir}
+%global flatpakoptions --with-beanshell-jar=/app/share/java/bsh.jar --with-commons-logging-jar=/app/share/java/commons-logging.jar --with-flute-jar=/app/share/java/flute.jar --with-jfreereport-jar=/app/share/java/flow-engine.jar --with-libbase-jar=/app/share/java/libbase.jar --with-libfonts-jar=/app/share/java/libfonts.jar --with-libformula-jar=/app/share/java/libformula.jar --with-liblayout-jar=/app/share/java/liblayout.jar --with-libloader-jar=/app/share/java/libloader.jar --with-librepository-jar=/app/share/java/librepository.jar --with-libserializer-jar=/app/share/java/libserializer.jar --with-libxml-jar=/app/share/java/libxml.jar --with-sac-jar=/app/share/java/sac.jar FIREBIRDCONFIG=%{_libdir}/fb_config QT4INC=%{_includedir}
+%if 0%{?rhel}
+%global flatpakoptions %{flatpakoptions} --with-boost-libdir=%{_libdir}
+%endif
 %endif
 
 # TODO: enable coinmp?