configure: Support the capturing of CFLAGS and CXXFLAGS at configure time.

These variables can now be set via configure time via environment
variables like so:

	CFLAGS=-g ./configure

and subsequent builds will remember these values. The values can
still be overridden at compile time by passing make variables:

      make CFLAGS=-O2

The CXXFLAGS variable is optional. If unset at either configure
time or at compile time, it will inherit its value from the
CFLAGS variable. (Though if explicitly set at configure time
it must be explicitly overriden at compile time---just overriding
CFLAGS will not override CXXFLAGS as well.)

2 files changed, 8 insertions, 3 deletions

diff --git a/Makefile b/Makefile
index 889a78c9..d112be6a 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,3 @@
-# Default FLAGS, (can be overridden by user such as "make CFLAGS=-g")
-CFLAGS=-O2
-
 WARN_CXXFLAGS=-Wall -Wextra -Wwrite-strings -Wswitch-enum
 WARN_CFLAGS=$(WARN_CXXFLAGS) -Wmissing-declarations
 
diff --git a/configure b/configure
index 488b3bd7..ff8baa5e 100755
--- a/configure
+++ b/configure
@@ -2,6 +2,8 @@
 
 CC=${CC:-gcc}
 CXX=${CXX:-g++}
+CFLAGS=${CFLAGS:--O2}
+CXXFLAGS=${CXXFLAGS:-\$(CFLAGS)}
 
 # defaults
 PREFIX=/usr/local
@@ -195,6 +197,12 @@ CC = ${CC}
 # The C++ compiler to use
 CXX = ${CXX}
 
+# Default FLAGS for C compiler (can be overridden by user such as "make CFLAGS=-g")
+CFLAGS = ${CFLAGS}
+
+# Default FLAGS for C++ compiler (can be overridden by user such as "make CXXFLAGS=-g")
+CXXFLAGS = ${CXXFLAGS}
+
 # The prefix to which notmuch should be installed
 prefix = ${PREFIX}