warning configuring postgres from source on OS X with uuid

configure: WARNING: uuid.h: present but cannot be compiled
configure: WARNING: uuid.h: check for missing prerequisite headers?
configure: WARNING: uuid.h: see the Autoconf documentation
configure: WARNING: uuid.h: section "Present But Cannot Be Compiled"
configure: WARNING: uuid.h: proceeding with the preprocessor's result
configure: WARNING: uuid.h: in the future, the compiler will take precedence
configure: WARNING: ## ---------------------------------------- ##
configure: WARNING: ## Report this to pgsql-bugs(at)postgresql(dot)org ##
configure: WARNING: ## ---------------------------------------- ##

configure command:
./configure CC=/usr/bin/clang CXX=/usr/bin/clang++ \
"CFLAGS=-arch x86_64 -I/usr/local/OSSP-uuid/include" \
"CXXFLAGS=-arch x86_64 -I/usr/local/OSSP-uuid/include" \
"CPPFLAGS=-I/usr/local/OSSP-uuid/include" \
"LDFLAGS=-arch x86_64 -L/usr/local/OSSP-uuid/lib"
--prefix=/usr/local/postgresql-8.4.21 --with-ossp-uuid

OS: OS X 10.9.3

uname -a: Darwin shadowfax.local 13.2.0 Darwin Kernel Version 13.2.0:
Thu Apr 17 23:03:13 PDT 2014; root:xnu-2422.100.13~1/RELEASE_X86_64 x86_64

postgres version: 8.4.21 (the same using 9.3.4)

clang --version
Apple LLVM version 5.1 (clang-503.0.40) (based on LLVM 3.4svn)
Target: x86_64-apple-darwin13.2.0
Thread model: posix

and "make" in contrib folder obtains:

/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/gethostuuid.h:39:25:
error: expected identifier
int gethostuuid(uuid_t, const struct timespec *)
__OSX_AVAILABLE_STARTING(__MAC_10_5, __IPHONE_NA);
^
In file included from uuid-ossp.c:27:
/usr/local/OSSP-uuid/include/uuid.h:94:24: error: typedef redefinition
with different types ('struct uuid_st' vs '__darwin_uuid_t' (aka
'unsigned char [16]'))
typedef struct uuid_st uuid_t;
^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/sys/_types/_uuid_t.h:30:25:
note: previous definition is here
typedef __darwin_uuid_t uuid_t;
^
In file included from uuid-ossp.c:27:
/usr/local/OSSP-uuid/include/uuid.h:107:22: error: conflicting types for
'uuid_compare'
extern uuid_rc_t uuid_compare (const uuid_t *_uuid, const uuid_t
*_uuid2, int *_result);
^
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.9.sdk/usr/include/uuid/uuid.h:55:5:
note: previous declaration is here
int uuid_compare(const uuid_t uu1, const uuid_t uu2);
^
3 errors generated.
make[1]: *** [uuid-ossp.o] Error 1
make: *** [all] Error 2

Feel free to ask if I can help in some way

Edoardo