Fix macOS .dylib build when VERSION contains letters.

macOS builds with --disable-static fail to link if the version number
contains letters because of the -current_version and
-compatibility_version arguments (current version is 0.9.28rc).

This commit adds a new MACOS_DYLIB_VERSION variable to config.mak for
builds that target macOS. It has no impact on other targets.

Makefile

@@ -55,8 +55,8 @@ else
       # `make test' when libtcc.dylib is used (configure --disable-static), so
       # we bake a relative path into the binary. $libdir is used after install.
       LINK_LIBTCC += -Wl,-rpath,"@executable_path/$(TOP)" -Wl,-rpath,"$(libdir)"
-      DYLIBVER += -current_version $(VERSION)
-      DYLIBVER += -compatibility_version $(VERSION)
+      DYLIBVER += -current_version $(MACOS_DYLIB_VERSION)
+      DYLIBVER += -compatibility_version $(MACOS_DYLIB_VERSION)
     endif
   endif
  endif

configure

@@ -602,6 +602,12 @@ echo "VERSION = $version" >> config.mak
 echo "#define TCC_VERSION \"$version\"" >> $TMPH
 echo "@set VERSION $version" > config.texi
 
+if test "$targetos" = "Darwin"; then
+  # On macOS, -current_version and -compatibility_version must not contain letters.
+  macos_dylib_version=`echo $version | sed 's/[^0-9.]//g'`
+  echo "MACOS_DYLIB_VERSION = $macos_dylib_version" >> config.mak
+fi
+
 if test "$source_path_used" = "yes" ; then
     case $source_path in
        /*) echo "TOPSRC=$source_path";;