Build: make it possible to assign macro definitions for specific outputs

Sometimes, some specific program or object file might need an extra
macro definition of its own.  This allows that to be easily done.

Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/7553)

Configurations/README

diff --git a/Configurations/README b/Configurations/README
index 9fd4922..1c67f75 100644
--- a/Configurations/README
+++ b/Configurations/README
@@ -467,6 +467,10 @@
 
     INCLUDE[foo]=include
 
+It's also possible to specify C macros that should be defined:
+
+    DEFINE[foo]=FOO BAR=1
+
 In some cases, one might want to generate some source files from
 others, that's done as follows:
 

Configurations/README.design

diff --git a/Configurations/README.design b/Configurations/README.design
index 8c50a92..c0b05bd 100644
--- a/Configurations/README.design
+++ b/Configurations/README.design
@@ -41,9 +41,10 @@
 (PROGRAM_NO_INST etc) to specify end products that shouldn't get
 installed.
 
-The variables SOURCE, DEPEND and INCLUDE are indexed by a produced
-file, and their values are the source used to produce that particular
-produced file, extra dependencies, and include directories needed.
+The variables SOURCE, DEPEND, INCLUDE and DEFINE are indexed by a
+produced file, and their values are the source used to produce that
+particular produced file, extra dependencies, include directories
+needed, or C macros to be defined.
 
 All their values in all the build.info throughout the source tree are
 collected together and form a set of programs, libraries, engines and

Configurations/common.tmpl

diff --git a/Configurations/common.tmpl b/Configurations/common.tmpl
index 4a08655..b7d2a07 100644
--- a/Configurations/common.tmpl
+++ b/Configurations/common.tmpl
@@ -85,6 +85,7 @@
                              deps => $unified_info{depends}->{$src},
                              incs => [ @{$unified_info{includes}->{$obj}},
                                        @{$unified_info{includes}->{$bin}} ],
+                             defs => $unified_info{defines}->{$obj},
                              %opts);
          foreach (@{$unified_info{depends}->{$src}}) {
              dogenerate($_, $obj, $bin, %opts);
@@ -107,6 +108,7 @@
                          deps => $unified_info{depends}->{$obj},
                          incs => [ @{$unified_info{includes}->{$obj}},
                                    @{$unified_info{includes}->{$bin}} ],
+                         defs => $unified_info{defines}->{$obj},
                          %opts);
          foreach ((@{$unified_info{sources}->{$obj}},
                    @{$unified_info{depends}->{$obj}})) {