Correct CI script, correct ICU testing config.

.github/workflows/ci.yml

@@ -88,7 +88,7 @@ jobs:
         run: sudo apt install g++-9 g++-10
       - name: Test
         run: ${{ matrix.compiler }} -std=${{ matrix.standard }}  -I../../include *.cpp ../../src/*.cpp -o regress -licuuc -licudata -licu18n && ./regress
-        working-directory: $GITHUB_WORKSPACE/test/regress
+        working-directory: ./test/regress
   ubuntu-bionic:
     runs-on: ubuntu-18.04
     strategy:

test/regress/test_icu.cpp

@@ -21,11 +21,13 @@
 //
 #include <boost/regex/config.hpp>
 
+#ifdef BOOST_REGEX_STANDALONE
 #ifdef __has_include
-#if __has_include(<unicode/utypes.h>)
+#if __has_include(<unicode/utypes.h>) && __has_include(<unicode/uchar.h>) && __has_include(<unicode/coll.h>)
 #define BOOST_HAS_ICU
 #endif
 #endif
+#endif
 
 #if defined(BOOST_HAS_ICU) && !defined(BOOST_NO_STD_WSTRING)