Allow Mac builds to use whatever the installed SDK is. Bump the minimum

supported target up to 10.9 (Mavericks).

Author: eliotmiranda

build.macos32x86/common/Makefile.flags

@@ -14,11 +14,15 @@ else # Allow Makefile to set specific SDK
 override SDK:=$(realpath $(addprefix $(SDKsDIR)/, $(SDK)))
 endif
 ifeq ($(strip $(SDK)),)
-$(error could not find a valid SDK)
+  ifeq ($(wildcard $(realpath $(addprefix $(SDKsDIR)/,MacOSX.sdk))),)
+	$(error could not find a valid SDK)
+  else
+	SDK:=$(realpath $(addprefix $(SDKsDIR)/,MacOSX.sdk))
+  endif
 endif
 TARGET_ARCH:=i386
 ifeq ($(TARGET_VERSION_MIN),) # Allow Makefile to set TARGET_VERSION_MIN
-TARGET_VERSION_MIN:=10.7
+TARGET_VERSION_MIN:=10.9
 endif
 
 # Determine where to install plugins in the .app bundle using the Squeak

build.macos64ARMv8/common/Makefile.flags

@@ -14,7 +14,11 @@ else # Allow Makefile to set specific SDK
 override SDK:=$(realpath $(addprefix $(SDKsDIR)/, $(SDK)))
 endif
 ifeq ($(strip $(SDK)),)
-$(error could not find a valid SDK)
+  ifeq ($(wildcard $(realpath $(addprefix $(SDKsDIR)/,MacOSX.sdk))),)
+	$(error could not find a valid SDK)
+  else
+	SDK:=$(realpath $(addprefix $(SDKsDIR)/,MacOSX.sdk))
+  endif
 endif
 TARGET_ARCH:=arm64
 #TARGET_CPU:=apple-a12

build.macos64x64/common/Makefile.flags

@@ -14,11 +14,15 @@ else # Allow Makefile to set specific SDK
 override SDK:=$(realpath $(addprefix $(SDKsDIR)/, $(SDK)))
 endif
 ifeq ($(strip $(SDK)),)
-$(error could not find a valid SDK)
+  ifeq ($(wildcard $(realpath $(addprefix $(SDKsDIR)/,MacOSX.sdk))),)
+	$(error could not find a valid SDK)
+  else
+	SDK:=$(realpath $(addprefix $(SDKsDIR)/,MacOSX.sdk))
+  endif
 endif
 TARGET_ARCH:=x86_64
 ifeq ($(TARGET_VERSION_MIN),) # Allow Makefile to set TARGET_VERSION_MIN
-TARGET_VERSION_MIN:=10.7
+TARGET_VERSION_MIN:=10.9
 endif
 
 # Determine where to install plugins in the .app bundle using the Squeak