Move configurable variables to the top

Define variables that are meant to be possibly overridden on the make
command line (or in a parent makefile) at the top. In particular, define
them before including the crypto and framework makefiles, so these makefiles
can use the default values if there's no parent setting.

Also move some internal variables earlier or later, so that a subsequent
refactoring step can have things in the right order in the mbedtls
per-directory makefile:

1. Define variables consumed by the per-directory crypto makefile.
2. Include the per-directory crypto makefile.
3. Use variables defined by the per-directory crypto makefile.

Signed-off-by: Gilles Peskine <[email protected]>

scripts/common.make

@@ -1,3 +1,16 @@
+CFLAGS	?= -O2
+WARNING_CFLAGS ?= -Wall -Wextra -Wformat=2 -Wno-format-nonliteral
+WARNING_CXXFLAGS ?= -Wall -Wextra -Wformat=2 -Wno-format-nonliteral -std=c++11 -pedantic
+LDFLAGS ?=
+
+PERL ?= perl
+
+ifdef WINDOWS
+PYTHON ?= python
+else
+PYTHON ?= $(shell if type python3 >/dev/null 2>/dev/null; then echo python3; else echo python; fi)
+endif
+
 ifndef MBEDTLS_PATH
 MBEDTLS_PATH := ..
 endif
@@ -18,11 +31,6 @@ include $(MBEDTLS_PATH)/framework/exported.make
 
 include $(MBEDTLS_PATH)/scripts/crypto-common.make
 
-CFLAGS	?= -O2
-WARNING_CFLAGS ?= -Wall -Wextra -Wformat=2 -Wno-format-nonliteral
-WARNING_CXXFLAGS ?= -Wall -Wextra -Wformat=2 -Wno-format-nonliteral -std=c++11 -pedantic
-LDFLAGS ?=
-
 # To compile on SunOS: add "-lsocket -lnsl" to LDFLAGS
 
 LOCAL_CFLAGS = $(WARNING_CFLAGS) -I$(MBEDTLS_TEST_PATH)/include \
@@ -130,14 +138,6 @@ else # Not building for Windows
   endif
 endif
 
-PERL ?= perl
-
-ifdef WINDOWS
-PYTHON ?= python
-else
-PYTHON ?= $(shell if type python3 >/dev/null 2>/dev/null; then echo python3; else echo python; fi)
-endif
-
 # See root Makefile
 GEN_FILES ?= yes
 ifdef GEN_FILES