enable -gdwarf-4 by default if possible

http://lists.freedesktop.org/archives/libreoffice/2011-December/021638.html

configure.in

@@ -3820,6 +3820,24 @@ fi
 AC_SUBST(HAVE_GCC_VISIBILITY_FEATURE)
 AC_SUBST(HAVE_GCC_VISIBILITY_BROKEN)
 
+dnl ===================================================================
+dnl gcc DWARF-4 support (smaller debug info)
+dnl ===================================================================
+if test "$GCC" = "yes"; then
+    AC_MSG_CHECKING([whether $CC supports -gdwarf-4])
+    save_CFLAGS=$CFLAGS
+    CFLAGS="$CFLAGS -Werror -gdwarf-4"
+    AC_LINK_IFELSE([AC_LANG_PROGRAM([[]], [[ return 0; ]])],[ HAVE_GCC_DWARF_4=TRUE ],[])
+    CFLAGS=$save_CFLAGS
+    if test "$HAVE_GCC_DWARF_4" = "TRUE"; then
+        AC_MSG_RESULT([yes])
+    else
+        AC_MSG_RESULT([no])
+    fi
+fi
+
+AC_SUBST(HAVE_GCC_DWARF_4)
+
 dnl ===================================================================
 dnl allocator
 dnl ===================================================================

set_soenv.in

@@ -1779,6 +1779,7 @@ ToFile( "HAVE_GCC_VISIBILITY_FEATURE",
 		"@HAVE_GCC_VISIBILITY_FEATURE@", "e" );
 ToFile( "HAVE_GCC_VISIBILITY_BROKEN",
         "@HAVE_GCC_VISIBILITY_BROKEN@", "e" );
+ToFile( "HAVE_GCC_DWARF_4","@HAVE_GCC_DWARF_4@","e" );
 ToFile( "HAVE_LD_HASH_STYLE","@HAVE_LD_HASH_STYLE@","e" );
 ToFile( "WITH_LINKER_HASH_STYLE","@WITH_LINKER_HASH_STYLE@","e" );
 ToFile( "HAVE_LD_BSYMBOLIC_FUNCTIONS",

solenv/gbuild/platform/WNT_INTEL_GCC.mk

@@ -99,6 +99,9 @@ gb_LinkTarget_LDFLAGS += -shared-libgcc
 endif
 
 gb_DEBUG_CFLAGS := -ggdb3 -finline-limit=0 -fno-inline -fno-default-inline
+ifeq ($(HAVE_GCC_DWARF_4),TRUE)
+gb_DEBUG_CFLAGS += -gdwarf-4
+endif
 
 gb_STDLIBS := \
 	mingwthrd \
@@ -152,6 +155,10 @@ gb_LinkTarget_CXXFLAGS := $(gb_CXXFLAGS) $(gb_CXXFLAGS_WERROR)
 ifeq ($(gb_SYMBOL),$(true))
 gb_LinkTarget_CXXFLAGS += -ggdb2
 gb_LinkTarget_CFLAGS += -ggdb2
+ifeq ($(HAVE_GCC_DWARF_4),TRUE)
+gb_LinkTarget_CXXFLAGS += -gdwarf-4
+gb_LinkTarget_CFLAGS += -gdwarf-4
+endif
 endif
 
 gb_LinkTarget_INCLUDE +=\

solenv/gbuild/platform/unxgcc.mk

@@ -162,6 +162,9 @@ gb_LINKEROPTFLAGS := -Wl,-O1
 endif
 
 gb_DEBUG_CFLAGS := -ggdb3 -finline-limit=0 -fno-inline -fno-default-inline
+ifeq ($(HAVE_GCC_DWARF_4),TRUE)
+gb_DEBUG_CFLAGS += -gdwarf-4
+endif
 
 gb_COMPILERNOOPTFLAGS := -O0
 
@@ -206,6 +209,10 @@ gb_LinkTarget_CXXFLAGS := $(gb_CXXFLAGS) $(gb_CXXFLAGS_WERROR)
 ifeq ($(gb_SYMBOL),$(true))
 gb_LinkTarget_CXXFLAGS += -ggdb2
 gb_LinkTarget_CFLAGS += -ggdb2
+ifeq ($(HAVE_GCC_DWARF_4),TRUE)
+gb_LinkTarget_CXXFLAGS += -gdwarf-4
+gb_LinkTarget_CFLAGS += -gdwarf-4
+endif
 endif
 
 # note that `cat $(extraobjectlist)` is needed to build with older gcc versions, e.g. 4.1.2 on SLED10