Add openssl installation to some bootstrappers

- The others seem to either be platforms where openssl is part of the
   base system, or where I can't quickly confirm that it's safe to ask
   for installation of something called "openssl".

 - If we miss any platforms, the OCSP checking code in "certbot
   certificates" should fail gracefully.

letsencrypt-auto-source/letsencrypt-auto

@@ -289,6 +289,7 @@ BootstrapDebCommon() {
     gcc \
     $augeas_pkg \
     libssl-dev \
+    openssl \
     libffi-dev \
     ca-certificates \
 
@@ -535,6 +536,7 @@ BootstrapMageiaCommon() {
            git \
            gcc \
            python-augeas \
+           openssl \
            libopenssl-devel \
            libffi-devel \
            rootcerts

letsencrypt-auto-source/pieces/bootstrappers/deb_common.sh

@@ -99,6 +99,7 @@ BootstrapDebCommon() {
     gcc \
     $augeas_pkg \
     libssl-dev \
+    openssl \
     libffi-dev \
     ca-certificates \
 

letsencrypt-auto-source/pieces/bootstrappers/mageia_common.sh

@@ -12,6 +12,7 @@ BootstrapMageiaCommon() {
            git \
            gcc \
            python-augeas \
+           openssl \
            libopenssl-devel \
            libffi-devel \
            rootcerts