merge revision(s) 6f3aff3961a4c5ce87e05096a1a9dcf1055b7647: [Backport #19289]

	[Bug #19289] Retain `ruby_abi_version` function

	A few extension libraries, to hide all symbols except for necessary to
	load, hardcode the symbols to be exported in symbol list files for
	linker without even checking by `have_func`.  As a workaround for such
	libraries, retain `ruby_abi_version` symbol always even in released
	versions for now.
	---
	 include/ruby/internal/abi.h | 7 +++++--
	 1 file changed, 5 insertions(+), 2 deletions(-)

2 files changed, 6 insertions, 3 deletions

diff --git a/include/ruby/internal/abi.h b/include/ruby/internal/abi.h
index d67aa0d509..44111a0055 100644
--- a/include/ruby/internal/abi.h
+++ b/include/ruby/internal/abi.h
@@ -31,6 +31,7 @@
 #if defined(HAVE_FUNC_WEAK) && !defined(_WIN32) && !defined(__MINGW32__) && !defined(__CYGWIN__)
 # define RUBY_DLN_CHECK_ABI
 #endif
+#endif  /* RUBY_ABI_VERSION */
 
 #ifdef RUBY_DLN_CHECK_ABI
 
@@ -41,7 +42,11 @@ extern "C" {
 RUBY_FUNC_EXPORTED unsigned long long __attribute__((weak))
 ruby_abi_version(void)
 {
+# ifdef RUBY_ABI_VERSION
     return RUBY_ABI_VERSION;
+# else
+    return 0;
+# endif
 }
 
 # ifdef __cplusplus
@@ -51,5 +56,3 @@ ruby_abi_version(void)
 #endif
 
 #endif
-
-#endif
diff --git a/version.h b/version.h
index 74eb7be93a..fb6a28ab79 100644
--- a/version.h
+++ b/version.h
@@ -11,7 +11,7 @@
 # define RUBY_VERSION_MINOR RUBY_API_VERSION_MINOR
 #define RUBY_VERSION_TEENY 0
 #define RUBY_RELEASE_DATE RUBY_RELEASE_YEAR_STR"-"RUBY_RELEASE_MONTH_STR"-"RUBY_RELEASE_DAY_STR
-#define RUBY_PATCHLEVEL 19
+#define RUBY_PATCHLEVEL 20
 
 #include "ruby/version.h"
 #include "ruby/internal/abi.h"