Allow low and high value of CLAMP to be equal

Can for example occur in RichString_setAttrn(), when pausing and
resuming process tracing:

    htop: RichString.c:56: void RichString_setAttrn(RichString *, int, int, int): Assertion `(0) < (this->chlen - 1)' failed.

    ./htop(backtrace+0x5b)[0x45d9eb]
    ./htop(CRT_handleSIGSEGV+0x189)[0x4ebab9]
    /lib/x86_64-linux-gnu/libpthread.so.0(+0x14140)[0x7fd249d35140]
    /lib/x86_64-linux-gnu/libc.so.6(gsignal+0x141)[0x7fd249b6ac41]
    /lib/x86_64-linux-gnu/libc.so.6(abort+0x123)[0x7fd249b54537]
    /lib/x86_64-linux-gnu/libc.so.6(+0x2540f)[0x7fd249b5440f]
    /lib/x86_64-linux-gnu/libc.so.6(+0x345c2)[0x7fd249b635c2]
    ./htop(RichString_setAttrn+0x234)[0x526de4]
    ./htop(RichString_setAttr+0x50)[0x5275c0]
    ./htop(Panel_draw+0x17b6)[0x514c26]
    ./htop(InfoScreen_run+0x305)[0x4fe7a5]
    ./htop[0x4d59d8]
    ./htop[0x5029cf]
    ./htop(ScreenManager_run+0x69f)[0x52a82f]
    ./htop(main+0x704)[0x4f8774]
    /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xea)[0x7fd249b55cca]
    ./htop(_start+0x2a)[0x4268ea]

1 files changed, 1 insertions, 1 deletions

diff --git a/Macros.h b/Macros.h
index e42cbe53..2f92acb1 100644
--- a/Macros.h
+++ b/Macros.h
@@ -12,7 +12,7 @@
 #endif
 
 #ifndef CLAMP
-#define CLAMP(x, low, high)	(assert((low) < (high)), ((x) > (high)) ? (high) : MAXIMUM(x, low))
+#define CLAMP(x, low, high)	(assert((low) <= (high)), ((x) > (high)) ? (high) : MAXIMUM(x, low))
 #endif
 
 #ifndef ARRAYSIZE