Include PCRE2 in R 3.x on Debian 11 for Pango support

In Debian 11, Pango now depends on PCRE2, so R 3.x will not be compiled with
Pango support if we hide PCRE2 to prevent R 3.5 and 3.6 from taking an unnecessary
dependency on PCRE2.

To check if R 3.x was compiled without Pango support, look for this line in the
configure output:

checking whether pkg-config knows about cairo and pango... no

Or in R, check if the "bitmapType" option defaults to "Xlib" instead of "Cairo":

> getOption("bitmapType")
"Xlib"

builder/package.debian-11

@@ -4,10 +4,10 @@ if [[ ! -d /tmp/output/debian-11 ]]; then
   mkdir -p /tmp/output/debian-11
 fi
 
-# R 3.x requires PCRE1
-pcre_lib='libpcre2-dev'
+# R 3.x requires PCRE1. On Debian 11, R 3.x also requires PCRE2 for Pango support.
+pcre_lib_flags='-d libpcre2-dev'
 if [[ "${R_VERSION}" =~ ^3 ]]; then
-  pcre_lib='libpcre3-dev'
+  pcre_lib_flags='-d libpcre2-dev -d libpcre3-dev'
 fi
 
 fpm \
@@ -39,7 +39,7 @@ fpm \
   -d libpango-1.0-0 \
   -d libpangocairo-1.0-0 \
   -d libpaper-utils \
-  -d ${pcre_lib} \
+  ${pcre_lib_flags} \
   -d libpng16-16 \
   -d libreadline8 \
   -d libtcl8.6 \