build: fix the OS X and Clang builds.

bootstrap

@@ -36,7 +36,7 @@ aclocalflags="`sed -ne 's/^[ \t]*ACLOCAL_AMFLAGS[ \t]*=//p' Makefile.am 2>/dev/n
 
 # Check for automake
 amvers="no"
-for v in 11 10 9 8 7 6 5; do
+for v in 13 12 11 10 9 8 7 6 5; do
   if automake-1.${v} --version >/dev/null 2>&1; then
     amvers="-1.${v}"
     break

caca/caca.h

@@ -683,7 +683,7 @@ typedef struct cucul_buffer cucul_buffer_t;
 #       define CACA_DEPRECATED
 #   endif
 
-#   if defined __GNUC__ && __GNUC__ > 3
+#   if defined __GNUC__ && __GNUC__ > 3 && !defined __APPLE__
 #       define CACA_ALIAS(x) __attribute__ ((weak, alias(#x)))
 #   else
 #       define CACA_ALIAS(x)