Unify and simplify flags for older machines

Makefile

@@ -1,3 +1,5 @@
+CFLAGS = -O3 std=c99 -Wall -D_POSIX_C_SOURCE=200809L
+
 all:
 	@make -C tiff
 	@make -C hdf5

hdf5/Makefile

@@ -1,7 +1,7 @@
-SRC = hdf5perf.c
-BIN = hdf5perf
+SRC      = hdf5perf.c
+BIN      = hdf5perf
 PKG_DEPS = glib-2.0
-CFLAGS = -Wall -Werror -std=c99 -O3 -DH5_USE_16_API
-LDFLAGS = -lhdf5
+CFLAGS  += -DH5_USE_16_API
+LDFLAGS += -lhdf5
 
 include ../c.mk

tiff/Makefile

@@ -1,6 +1,6 @@
-BIN=tiffperf
-SRC=tiffperf.c
-PKG_DEPS = libtiff-4 glib-2.0
-CFLAGS = -g -ggdb
+BIN      = tiffperf
+SRC      = tiffperf.c
+PKG_DEPS = glib-2.0
+LDFLAGS += -ltiff
 
 include ../c.mk