Issue-4402 Boost compile error on macOS Catalina

Patch boost build from boostorg/build#560

Author: svarnau

build_definitions/boost.py

@@ -38,7 +38,8 @@ def __init__(self):
             BUILD_GROUP_INSTRUMENTED)
         self.dir = '{}_{}'.format(self.name, self.underscored_version)
         self.copy_sources = True
-        self.patches = ['boost-1-69-remove-pending-integer_log2-include.patch']
+        self.patches = ['boost-1-69-remove-pending-integer_log2-include.patch',
+                        'boost-1-69-mac-compiler-flags.patch']
         self.patch_strip = 1
 
     def build(self, builder):

patches/boost-1-69-mac-compiler-flags.patch

@@ -0,0 +1,21 @@
+diff --git a/darwin.orig b/darwin.jam
+index 8d477410b..97e7ecb85 100644
+--- a/tools/build/src/tools/darwin.jam
++++ b/tools/build/src/tools/darwin.jam
+@@ -137,13 +137,14 @@ rule init ( version ? : command * : options * : requirement * )
+     # - Set the toolset generic common options.
+     common.handle-options darwin : $(condition) : $(command) : $(options) ;
+     
++    real-version = [ regex.split $(real-version) \\. ] ;
+     # - GCC 4.0 and higher in Darwin does not have -fcoalesce-templates.
+-    if $(real-version) < "4.0.0"
++    if [ version.version-less $(real-version) : 4 0 ]
+     {
+         flags darwin.compile.c++ OPTIONS $(condition) : -fcoalesce-templates ;
+     }
+     # - GCC 4.2 and higher in Darwin does not have -Wno-long-double.
+-    if $(real-version) < "4.2.0"
++    if [ version.version-less $(real-version) : 4 2 ]
+     {
+         flags darwin.compile OPTIONS $(condition) : -Wno-long-double ;
+     }