Fix compilation with Sun CC

- Add the CFLAGS variable to config.mak.in to override the Makefile's
  default, which is gcc-specific and won't work with Sun CC.
- Prefer "cc" over "gcc", because Pasky's Git.pm will not compile with gcc
  on Solaris at all. On Linux and the free BSDs "cc" is linked to "gcc"
  anyway.
- Set correct flag to generate position-independent code.
- Add "-xO3" (= use default optimization level) to CFLAGS.

Signed-off-by: Dennis Stosberg <dennis@stosberg.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Makefile

@@ -112,6 +112,7 @@ uname_P := $(shell sh -c 'uname -p 2>/dev/null || echo not')
 # CFLAGS and LDFLAGS are for the users to override from the command line.
 
 CFLAGS = -g -O2 -Wall
+PIC_FLAG = -fPIC
 LDFLAGS =
 ALL_CFLAGS = $(CFLAGS)
 ALL_LDFLAGS = $(LDFLAGS)
@@ -402,6 +403,9 @@ endif
 ifneq (,$(findstring arm,$(uname_M)))
 	ARM_SHA1 = YesPlease
 endif
+ifeq ($(uname_M),sun4u)
+	USE_PIC = YesPlease
+endif
 ifeq ($(uname_M),x86_64)
 	USE_PIC = YesPlease
 endif
@@ -544,7 +548,7 @@ endif
 endif
 endif
 ifdef USE_PIC
-	ALL_CFLAGS += -fPIC
+	ALL_CFLAGS += $(PIC_FLAG)
 endif
 ifdef NO_ACCURATE_DIFF
 	BASIC_CFLAGS += -DNO_ACCURATE_DIFF

config.mak.in

@@ -2,6 +2,8 @@
 # @configure_input@
 
 CC = @CC@
+CFLAGS = @CFLAGS@
+PIC_FLAG = @PIC_FLAG@
 AR = @AR@
 TAR = @TAR@
 #INSTALL = @INSTALL@		# needs install-sh or install.sh in sources

configure.ac

@@ -95,7 +95,14 @@ AC_SUBST(PYTHON_PATH)
 ## Checks for programs.
 AC_MSG_NOTICE([CHECKS for programs])
 #
-AC_PROG_CC
+AC_PROG_CC([cc gcc])
+if test -n "$GCC"; then
+	PIC_FLAG="-fPIC"
+else
+	AC_CHECK_DECL(__SUNPRO_C, [CFLAGS="$CFLAGS -xO3"; PIC_FLAG="-KPIC"])
+fi
+AC_SUBST(PIC_FLAG)
+
 #AC_PROG_INSTALL		# needs install-sh or install.sh in sources
 AC_CHECK_TOOL(AR, ar, :)
 AC_CHECK_PROGS(TAR, [gtar tar])