Add basic cross-compilation support.

Supports both autotools-like --host=... switch and Linux kernel-style
CROSS_COMPILE env var.

qb/config.libs.sh

@@ -4,9 +4,9 @@ check_switch_c NOUNUSED -Wno-unused-result
 add_define_make NOUNUSED "$HAVE_NOUNUSED"
 
 # There are still broken 64-bit Linux distros out there. :)
-[ -d /usr/lib64 ] && add_library_dirs /usr/lib64
+[ -z "$CROSS_COMPILE" ] && [ -d /usr/lib64 ] && add_library_dirs /usr/lib64
 
-[ -d /opt/local/lib ] && add_library_dirs /opt/local/lib
+[ -z "$CROSS_COMPILE" ] && [ -d /opt/local/lib ] && add_library_dirs /opt/local/lib
 
 if [ "$OS" = 'BSD' ]; then DYLIB=-lc; else DYLIB=-ldl; fi
 [ "$OS" = 'Darwin' ] && HAVE_X11=no # X11 breaks on recent OSXes even if present.

qb/qb.comp.sh

@@ -24,7 +24,7 @@ if [ "$USE_LANG_C" = 'yes' ]; then
 #include <stdio.h>
 int main(void) { puts("Hai world!"); return 0; }
 EOF
-	for CC in ${CC:=$(which gcc cc)} ''; do
+	for CC in ${CC:=$(which ${CROSS_COMPILE}gcc ${CROSS_COMPILE}cc)} ''; do
 		"$CC" -o "$TEMP_EXE" "$TEMP_C" >/dev/null 2>&1 && break
 	done
 	[ "$CC" ] || { echo "$ECHOBUF ... Not found. Exiting."; exit 1;}
@@ -40,7 +40,7 @@ if [ "$USE_LANG_CXX" = 'yes' ]; then
 #include <iostream>
 int main() { std::cout << "Hai guise" << std::endl; return 0; }
 EOF
-	for CXX in ${CXX:=$(which g++ c++)} ''; do
+	for CXX in ${CXX:=$(which ${CROSS_COMPILE}g++ ${CROSS_COMPILE}c++)} ''; do
 		"$CXX" -o "$TEMP_EXE" "$TEMP_CXX" >/dev/null 2>&1 && break
 	done
 	[ "$CXX" ] || { echo "$ECHOBUF ... Not found. Exiting."; exit 1;}

qb/qb.params.sh

@@ -16,6 +16,7 @@ LDFLAGS:    Linker flags
 
 General options:
 --prefix=\$path: Install path prefix
+--host=HOST: cross-compile to build programs to run on HOST
 --help: Show this help
 
 Custom options:
@@ -50,6 +51,7 @@ parse_input() # Parse stuff :V
 	while [ "$1" ]; do
 		case "$1" in
 			--prefix=*) PREFIX=${1##--prefix=};;
+			--host=*) CROSS_COMPILE=${1##--host=}-;;
 			--enable-*)
 				opt_exists "${1##--enable-}"
 				eval "HAVE_$opt=yes"