Fix bugs in ./configure

Fix bugs in ./configure wherein build.mk is written in src/, not mk/

configure

@@ -95,8 +95,8 @@ SONAME_FULL	= $(SONAME_SHORT).$(VERSION)
 
 EOF
 
-    cat <<EOF >> mk/build.mk
-PREFIX      = $PREFIX
+    cat <<EOF >> "$1"
+PREFIX		= $PREFIX
 EOF
 }
 
@@ -114,7 +114,7 @@ SONAME_FULL	= lib$(LIBNAME).$(VERSION).dylib
 
 EOF
 
-    cat <<EOF >> mk/build.mk
+    cat <<EOF >> "$1"
 PREFIX      = $PREFIX
 EOF
 }
@@ -136,7 +136,7 @@ EOF
         build_mk_append_generic "$1"
     fi
 
-	cat <<'EOF' >> mk/build.mk
+	cat <<'EOF' >> "$1"
 CWFLAGS		= -Wall
 COFLAGS		= -O2
 CFLAGS		= $(CGFLAGS) $(CWFLAGS) $(COFLAGS)
@@ -164,4 +164,4 @@ if [ ! -d "mk" ]; then
 fi
 
 config_h_create "src/config.h"
-build_mk_create "src/build.mk"
+build_mk_create "mk/build.mk"