Pass -std=c++11 when compiling files that include the ICU headers.  Without
this flag, compilation fails and causes Boost's build system to remove ICU
support.  Note that $(pkg-config --variable=CXXFLAGS icu-uc) includes
"-std=c++11", but Boost's build system does not use 'pkg-config'.

--- boost_1_66_0/libs/locale/build/Jamfile.v2.orig	2017-12-13 18:56:44.000000000 -0500
+++ boost_1_66_0/libs/locale/build/Jamfile.v2	2018-04-08 15:18:58.673025760 -0400
@@ -65,8 +65,8 @@
 
 if $(ICU_LINK)
 {
-    ICU_OPTS = <include>$(ICU_PATH)/include <linkflags>$(ICU_LINK) <dll-path>$(ICU_PATH)/bin <runtime-link>shared ;
-    ICU64_OPTS = <include>$(ICU_PATH)/include <linkflags>$(ICU_LINK) <dll-path>$(ICU_PATH)/bin64 <runtime-link>shared ;
+    ICU_OPTS = <include>$(ICU_PATH)/include <cxxflags>-std=c++11 <linkflags>$(ICU_LINK) <dll-path>$(ICU_PATH)/bin <runtime-link>shared ;
+    ICU64_OPTS = <include>$(ICU_PATH)/include <cxxflags>-std=c++11 <linkflags>$(ICU_LINK) <dll-path>$(ICU_PATH)/bin64 <runtime-link>shared ;
 }
 else
 {
@@ -121,6 +121,7 @@
     explicit icuuc icudt icuin ;
 
     ICU_OPTS =   <include>$(ICU_PATH)/include 
+      <cxxflags>-std=c++11
       <library>icuuc/<link>shared/<runtime-link>shared 
       <library>icudt/<link>shared/<runtime-link>shared 
       <library>icuin/<link>shared/<runtime-link>shared
@@ -180,6 +181,7 @@
     explicit icuuc_64 icudt_64 icuin_64 ;
 
     ICU64_OPTS =   <include>$(ICU_PATH)/include 
+      <cxxflags>-std=c++11
       <library>icuuc_64/<link>shared/<runtime-link>shared 
       <library>icudt_64/<link>shared/<runtime-link>shared 
       <library>icuin_64/<link>shared/<runtime-link>shared
--- boost_1_66_0/libs/regex/build/Jamfile.v2.orig	2017-12-13 18:56:48.000000000 -0500
+++ boost_1_66_0/libs/regex/build/Jamfile.v2	2018-04-08 15:20:40.865532505 -0400
@@ -44,7 +44,7 @@
 
    if $(ICU_LINK)
    {
-      ICU_OPTS = <include>$(ICU_PATH)/include <linkflags>$(ICU_LINK) <dll-path>$(ICU_PATH)/bin <define>BOOST_HAS_ICU=1 <runtime-link>shared ;
+      ICU_OPTS = <include>$(ICU_PATH)/include <cxxflags>-std=c++11 <linkflags>$(ICU_LINK) <dll-path>$(ICU_PATH)/bin <define>BOOST_HAS_ICU=1 <runtime-link>shared ;
    }
    else
    {
@@ -78,6 +78,7 @@
 
       ICU_OPTS = 
          <include>$(ICU_PATH)/include 
+         <cxxflags>-std=c++11
          <runtime-link>shared:<library>icuuc/<link>shared
          <runtime-link>shared:<library>icudt/<link>shared
          <runtime-link>shared:<library>icuin/<link>shared
d=dff31d41d945bf4b25ad3014dac32561bfbb33a0'>mailmap: Update for self.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2020-05-13 09:30:26 +0300'>2020-05-13</span></td><td><a href='/guix/commit/.mailmap?id=3c986a7dc268756c097212de958f046b29b76c1b'>mailmap: Update entries for Nikita.</a><span class='msg-avail'>...</span></td><td>nikita</td></tr>
<tr><td><span title='2020-03-28 16:30:07 -0400'>2020-03-28</span></td><td><a href='/guix/commit/.mailmap?id=c2cf286c62933d2806ae17b8287520820bf87c7e'>Update email address and Savannah handle for Amin Bandali.</a><span class='msg-avail'>...</span></td><td>Amin Bandali</td></tr>
<tr><td><span title='2020-02-09 23:16:45 +0100'>2020-02-09</span></td><td><a href='/guix/commit/.mailmap?id=e81344428726f3dae5d2a2e7bb296f46fcde6cc5'>Update e-mail address for Jakob L. Kreuze.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2020-01-17 18:30:33 +0100'>2020-01-17</span></td><td><a href='/guix/commit/.mailmap?id=a3143063aeeecb5c02f75a6e1ddc0cc295e0e4f8'>Update email address for Amin Bandali.</a><span class='msg-avail'>...</span></td><td>Amin Bandali</td></tr>
<tr><td><span title='2019-12-19 11:35:23 -0600'>2019-12-19</span></td><td><a href='/guix/commit/.mailmap?id=4b3ff36228da17db980c98fe9e1669be613a5402'>Update email for Brett Gilio.</a><span class='msg-avail'>...</span></td><td>Brett Gilio</td></tr>
<tr><td><span title='2019-12-18 22:57:44 -0600'>2019-12-18</span></td><td><a href='/guix/commit/.mailmap?id=a7cdf124c0b28be6c4e750161c1341753eede7b8'>gnu: leocad: Update to 19.07.1.</a><span class='msg-avail'>...</span></td><td>Eric Bavier</td></tr>
<tr><td><span title='2019-05-03 08:45:55 +0200'>2019-05-03</span></td><td><a href='/guix/commit/.mailmap?id=3e85909044d8d9b492bcd2ecedde26d71794f145'>Correct email address for ison.</a><span class='msg-avail'>...</span></td><td>ison</td></tr>
<tr><td><span title='2019-03-18 15:05:08 +0100'>2019-03-18</span></td><td><a href='/guix/commit/.mailmap?id=47956fa0c24efcdcba3493f0231c30e9a39ec7df'>Correct name and email address for ng0.</a><span class='msg-avail'>...</span></td><td>ng0</td></tr>
<tr><td><span title='2019-01-21 10:10:43 +0100'>2019-01-21</span></td><td><a href='/guix/commit/.mailmap?id=e3634bd0a3480bde3aba5bd6d84d7aff25413207'>Update .mailmap.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>